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Report to the Chairman, Committee on the Judiciary, House of 
Representatives:

United States General Accounting Office:

GAO:

May 2004:

Overstay Tracking:

A Key Component of Homeland Security and a Layered Defense:

GAO-04-82:

GAO Highlights:

Highlights of GAO-04-82, a report to the Chairman of the Committee on 
the Judiciary, House of Representatives 

Why GAO Did This Study:

Each year, millions of visitors, foreign students, and immigrants come 
to the United States. Foreign visitors may enter on a legal temporary 
basis—that is, with an authorized period of admission that expires on a 
specific date—either (1) with temporary visas (generally for tourism, 
business, or work) or, in some cases, (2) as tourists or business 
visitors who are allowed to enter without visas. (The latter include 
Canadians and qualified visitors from 27 countries who enter under the 
visa waiver program.) The majority of visitors who are tracked depart 
on time, but others overstay—and since September 11, 2001, the question 
has arisen as to whether overstay issues might have an impact on 
domestic security. 

In this report, we (1) describe available data on the extent of 
overstaying, (2) report on weaknesses in the Department of Homeland 
Security’s long-standing overstay tracking system, and 
(3) provide some observations on the impact that tracking system 
weaknesses and significant levels of overstaying may have on domestic 
security.

We provided a draft of this report to the Department of Homeland 
Security and the Department of Justice. Both agencies informed us that 
they had no comments.

What GAO Found:

Significant numbers of foreign visitors overstay their authorized 
periods of admission. Based in part on its long-standing I-94 system 
for tracking arrivals and departures, the Department of Homeland 
Security (DHS) estimated the overstay population for January 2000 at 
2.3 million. But this estimate (1) excludes an unknown number of 
long-term overstays from Mexico and Canada, and by definition (2) 
excludes short-term overstays from these and other countries. 

Because of unresolved weaknesses in DHS’s long-standing tracking 
system (e.g., noncollection of some departure forms), there is no 
accurate list of overstays. Tracking system weaknesses make it 
difficult to monitor potentially suspicious aliens who enter the 
country legally—and limit immigration control options. Post-September 
11 operations identified thousands of overstays and other illegal 
immigrant workers who (despite limited background checks) had obtained 
critical infrastructure jobs and security badges with access to, for 
example, airport tarmacs and U.S. military bases. As of April 2004, 
federal investigators had arrested more than 1,360 illegal workers, 
while the majority had eluded apprehension. 

Together with other improvements, better information on overstays might 
contribute to a layered national defense that is better able to counter 
threats from foreign terrorists. A more comprehensive system, US-VISIT, 
the U.S. Visitor and Immigrant Status Indicator Technology, is being 
phased in. The design and implementation of US-VISIT, however, face a 
number of challenges. It is important that this new program avoid 
specific weaknesses associated with the long-standing system. Checking 
for these weaknesses might help identify difficult challenges in 
advance and—together with other efforts —enhance US-VISIT’s chances for 
eventual success as a tracking system. 

www.gao.gov/cgi-bin/getrpt?GAO-04-82.

To view the full product, including the scope and methodology, click on 
the link above. For more information, contact Nancy Kingsbury at (202) 
512-2700 or kingsburyn@gao.gov.

[End of section]

Contents:

Letter:

Background:

Objectives, Scope, and Methodology:

Results in Brief:

DHS's Estimate May Understate the Extent of Overstaying:

Unresolved Tracking System Weaknesses Heighten the Overstay Problem:

Overstay Issues May Complicate Efforts to Ensure Domestic Security:

Conclusion:

Agency Comments:

Appendix I: Copy of Form I-94:

Appendix II: Perimeter for Mexican Visitors Not Required to Complete 
Form I-94:

Appendix III: How DHS Estimated Illegal Immigrants:

Appendix IV: How DHS Estimated Overstays:

Appendix V: DHS I-94 Data, Mixing Real and False Cases, Fiscal Year 
2001:

Appendix VI: Four Prior Recommendations on Overstay Tracking, Data, or 
Estimates:

Appendix VII: Data from Operation Tarmac and Other Operations:

Appendix VIII: Key to References in Figure 1:

Overseas: Tracking Terrorists and Visa Issuance:

Border Security:

Internal Enforcement and Tracking:

Domestic Identity Fraud:

Critical Infrastructure Protection:

Aviation Security:

Tables:

Table 1: Overstay and Other Immigration Status Data on September 11 
Hijackers:

Table 2: Operation Tarmac Data for Selected Airports: Number of 
Overstays Arrested by Airport:

Table 3: Critical Infrastructure and Special-Event Operations: Data on 
Number of Overstays Arrested by Operation:

Table 4: DHS Classification of Apparent Overstays (A Mix of Real and 
False Cases) from I-94 Data by Arrival Mode, Fiscal Year 2001:

Table 5: DHS's Classification of Apparent Overstays (A Mix of Real and 
False Cases) from I-94 Data by Arrival Mode and Citizenship, Fiscal 
Year 2001:

Table 6: Numbers of Illegal Immigrant Workers (and Overstays) Arrested 
in Selected Operation Tarmac Airports, by Nationality:

Table 7: Illegal Immigrant Workers (and Overstays) Arrested in Critical 
Infrastructure and Special-Event Operations, by Nationality:

Figures:

Figure 1: A Layered Defense for Domestic Security and Selected GAO 
Products:

Figure 2: Sample of Border Crossing Card the U.S. Department of State 
Issues to Qualified Mexican Citizens:

Figure 3: Key Groups Covered and Not Covered by DHS's Overstay 
Estimate:

Figure 4: Change in the Size of the Foreign-Born Population, 1990-2003:

Figure 5: Form I-94:

Figure 6: Perimeter for Mexican Visitors Not Required to Complete Form 
I-94:

Abbreviations:

BCC: border crossing card:

CPS: Current Population Survey:

DHS: Department of Homeland Security:

DOJ: Department of Justice:

DOT: Department of Transportation:

EWI: entered without inspection:

ICE: Immigration and Customs Enforcement:

INS: Immigration and Naturalization Service:

NIIS: Nonimmigrant Information System:

NSEERS: National Security Entry and Exit Registration System:

POE: point of entry:

SAVE: Systematic Alien Verification program:

SSA: Social Security Administration:

TPS: temporary protected status:

TSA: Transportation Security Administration:

US-VISIT: United States Visitor and Immigrant Status Indicator 
Technology:

United States General Accounting Office:

Washington, DC 20548:

May 21, 2004:

The Honorable F. James Sensenbrenner, Jr.: 
Chairman: 
Committee on the Judiciary: 
House of Representatives:

Dear Chairman Sensenbrenner:

Reliable data are critical to support effective public policy decisions 
in the area of illegal immigration. Such data have often been lacking 
or inadequate. This report responds to your request that we review 
relevant information on a key group of illegal aliens--"overstays"--and 
provide observations on the potential effect of the quality of that 
information on domestic security.[Footnote 1] An overstay is a foreign 
citizen who entered the United States legally but stayed beyond his or 
her authorized period of admission.

Specifically, we (1) describe available data on the extent to which 
overstaying occurs, (2) report on weaknesses in the long-standing 
overstay tracking system, and (3) provide some observations on the 
effects that overstays--or deficiencies in our overstay tracking 
system--may have on domestic security.

Background:

Each year, millions of visitors, foreign students, and immigrants come 
to the United States. A visitor may enter on a legal temporary basis--
that is, with an authorized period of admission that expires on a 
specific date--either with a temporary visa (generally for tourism, 
business, or work) that the Department of State issues or, in some 
cases, as a tourist or business visitor who is allowed to enter without 
a visa. The latter category includes Canadians and qualified visitors 
from 27 countries who enter under the Visa Waiver Permanent 
program.[Footnote 2] A large majority of these visitors depart on time, 
but others overstay.

The term "overstay" is defined as follows:

An overstay is an illegal alien who was legally admitted to the United 
States for a specific authorized period but remained here after that 
period expired, without obtaining an extension or a change of status or 
meeting other specific conditions.[Footnote 3] Overstays who settle 
here are part of the illegal immigrant population.[Footnote 4]

Although overstays are sometimes referred to as visa overstays, we do 
not use that term in this report for two reasons. First, many visitors 
are allowed to enter the United States without visas and to remain for 
specific periods of time, which they may overstay.[Footnote 5] Second, 
a visitor can overstay an authorized period of admission set by a U.S. 
Department of Homeland Security (DHS) inspector at the border--even 
though that authorized period may be shorter than the period of the 
visitor's visa.[Footnote 6] (For example, a visitor with a 6-month 
multiple-entry visa from the Department of State might be issued a 6-
week period of admission by the DHS inspector and remain here for 7 
weeks, thus overstaying.)

Viewed in terms of individuals, the overstay process can be summarized 
as aliens' (1) legally visiting the United States, which for citizens 
of most nations is preceded by obtaining a passport and a visa and 
filling out Form I-94 at the U.S. border; (2) overstaying for a period 
that may range from a single day to weeks, months, or years; and, in 
some cases, (3) terminating their overstay status by exiting the United 
States or adjusting to legal permanent resident status (that is, 
obtaining a green card).[Footnote 7] Most long-term overstays appear to 
have economic motivations.

However, the overstay process can also be viewed in the context of a 
layered defense for domestic security, supported by agencies such as 
DHS, the U.S. Department of Justice (DOJ), and the Department of State, 
among others. Figure 1 illustrates the layered-defense concept and the 
many interrelated issues that we have analyzed in numerous reports--
ranging from the overseas tracking of terrorists to stateside security 
for critical infrastructure locations. Intelligence, investigation, 
and information sharing are the key ingredients supporting such a 
defense. A variety of immigration issues are potentially relevant.

Figure 1: A Layered Defense for Domestic Security and Selected GAO 
Products:

[See PDF for image]

Note: GAO products in this figure are listed with full bibliographic 
citations in appendix VIII.

[End of figure]

Progress in deploying and effectively using watch lists is ongoing. In 
2003, we reported that (1) the State Department, "with the help of 
other agencies, almost doubled the number of names and the amount of 
information" in its Consular Lookout and Support System but that (2) 
"the federal watch list environment has been characterized by a 
proliferation of [terrorist and watch list] systems, among which 
information sharing is occurring in some cases but not in 
others."[Footnote 8] Visitor biographical and biometric data are now 
being checked against selected watch list data, to verify visitors' 
identity, as part of the new U.S. Visitor and Immigrant Status 
Indicator Technology program (US-VISIT).[Footnote 9]

Keeping all dangerous persons and potential terrorist suspects from 
legally entering the United States is difficult because some do not 
match the expected characteristics of terrorists or suspicious persons. 
In addition, some--such as citizens of Canada or one of the 27 visa 
waiver countries--are not required to apply for visas and are not 
screened by the visa process. Terrorists may continue to slip through 
border defenses, and watch lists have therefore also been used for 
tracking foreign terrorists within the United States.[Footnote 10]

Overstay tracking--that is, recording visitors' entries and exits as 
well as their address information--also logically plays a 
role.[Footnote 11] Overstay issues have gained heightened attention 
because some of the hijackers of September 11, 2001, had overstayed 
their periods of admission.

Form I-94 (shown in appendix I) is the basis of DHS's long-standing 
system for tracking overstays.[Footnote 12] For visitors from most 
countries, the period of admission is authorized (or set) by a DHS 
inspector when they enter the United States legally and fill out this 
form. Each visitor is to give the top half of the form to the inspector 
and to retain the bottom half, which should be collected when the 
visitor departs the country. However, two major groups are exempt from 
filling out Form I-94 when they visit the United States for business or 
pleasure:

* Canadian citizens admitted for up to 6 months[Footnote 13] and:

* Mexican citizens entering the United States with a border crossing 
card (BCC, illustrated in fig. 2) at the southwestern border who intend 
to limit their stay to less than 72 hours and intend not to travel 
beyond a set perimeter, generally 25 miles from the border (see app. 
II, fig. 6).[Footnote 14]

Figure 2: Sample of Border Crossing Card the U.S. Department of State 
Issues to Qualified Mexican Citizens:

[See PDF for image]

[End of figure]

During fiscal years 1999 to 2003, the Department of State issued 6.4 
million Mexican BCCs. Because the majority of Canadian and Mexican BCC 
visits do not require Form I-94, the system based on this form cannot 
follow them--that is, cannot track them. No data indicate how many 
overstay. Overstay tracking should be possible for almost all other 
legal temporary visitors, including visitors from visa waiver 
countries, because they are required to fill out the form.

Objectives, Scope, and Methodology:

Our objectives were to:

* describe available data on the extent to which overstaying occurs,

* identify any weaknesses that might limit the utility of DHS's long-
standing overstay tracking system, and:

* provide some observations about the potential effect of overstays--as 
well as limitations of the overstay tracking system--on domestic 
security.

In examining these issues, our main information sources included (1) 
relevant GAO and other reports, (2) interviews we conducted with 
officials and staff at DHS and DOJ, and (3) a variety of data, 
including printouts from DHS's long-standing overstay tracking system 
(based on Form I-94), data that DHS developed, at our request, from 
Operation Tarmac (the sweep that identified overstays and other illegal 
immigrants working at U.S. airports) and other similar operations, and 
facts about the arrivals, departures, and overstay status of the 
September 11 hijackers and others involved in terrorist-related 
activities.

We assessed the reliability of these data sources by reviewing existing 
information about the data, interviewing agency officials knowledgeable 
about the data and the process by which they were collected, and 
reviewing the data for reasonableness and corroboration with other 
independent data sources. While we found and reported on weaknesses in 
the data, we determined that the data were sufficiently reliable for 
the purposes of this report.

Our scope did not include (1) aspects of illegal immigration or 
domestic security unrelated to overstaying or (2) elements of overstay 
enforcement additional to a system for tracking legal visitors' entries 
and exits (for example, resource allocation).

Our work was conducted in accordance with generally accepted government 
auditing standards between January 2003 and May 2004, primarily at DHS 
and DOJ headquarters in Washington, D.C. One visit to the southwest 
border was made to observe departure procedures.

Results in Brief:

Our analysis indicates that:

* The extent of overstaying is significant and may be understated by 
DHS's most recent estimate.

* DHS's long-standing system for tracking overstays has several 
weaknesses.

* While the magnitude of domestic security risks cannot be quantified, 
efforts to ensure domestic security are affected to some degree by the 
significant level of overstaying that apparently occurs and by 
limitations in DHS's long-standing overstay tracking system.

Significant numbers of foreign visitors overstay their authorized 
periods of admission. While reliable data are lacking, DHS has 
estimated the resident overstay population at 2.3 million as of January 
2000. Among other issues, this estimate omits an unknown number of 
long-term overstays from Mexico and Canada. It also does not cover 
short-term overstays who have not established residence here.

Unresolved weaknesses in DHS's long-standing system for tracking 
visitors' arrivals and departures (based on Form I-94) include, among 
others, noncollection of many departure forms and an inability to match 
departure forms to arrivals. As a result, there is no accurate list of 
overstays. The recently initiated US-VISIT program--a more 
comprehensive program--may address some of these weaknesses. While the 
design and implementation of US-VISIT face a number of challenges, we 
believe that it might be useful to determine whether the new program 
successfully avoids specific weaknesses associated with the long-
standing I-94 system. Together with other efforts, this might help 
identify some difficult challenges in advance and might enhance US-
VISIT's chances for eventual success as an overstay tracking system.

Turning to domestic security, although most long-term overstays appear 
to be motivated by economic opportunities, a few overstays have been 
identified as terrorists or involved in terrorist-related activities. 
Notably, some of the September 11 hijackers had overstayed. While we 
were not able to quantify specific risks, we observed that:

* Weaknesses in the overstay tracking system may hamper efforts to 
monitor potentially suspicious aliens who enter the country legally. 
Although the vast majority of visitors come only for business or 
pleasure, the few who are potential terrorists or terrorist supporters 
could present a threat to domestic security.

* These weaknesses effectively enable a form of illegal immigration, 
thus in some cases potentially affecting security. Overstays who settle 
here in large numbers can affect domestic security because they (like 
other illegal immigrants) are able to obtain jobs and security badges 
with fraudulent identity documents, thus gaining access to critical 
infrastructure locations, such as airports, or special events, like the 
Super Bowl--making efforts to secure these venues more difficult. For 
example, overstays with fraudulently obtained badges were found at 25 
of 26 airports examined.

Considering these points and viewing the overstay tracking system as 
one component of a layered national defense, we believe that an 
improved system could work together with other factors--especially 
intelligence, investigation, and information sharing--to help counter 
threats from foreign terrorists.

We provided a draft of this report to the Department of Homeland 
Security and the Department of Justice. Both agencies informed us that 
they had no comments.

DHS's Estimate May Understate the Extent of Overstaying:

Significant numbers of visitors overstay their authorized periods of 
admission. A January 2003 DHS estimate put the January 2000 resident 
overstay population at one-third of 7 million illegal immigrants, or 
2.3 million.[Footnote 15]

While the method DHS used to obtain this figure is complex, indirect, 
and marked by potential weaknesses, we identified three small-sample 
alternative data points that, taken together, provide some evidence 
that, in all likelihood, a substantial proportion of illegal immigrants 
are overstays. These three alternative data sources on illegal 
immigrants indicate varying--but uniformly substantial--percentages of 
overstays: 31 percent, 27 percent, and 57 percent.

At the same time, we found that DHS's estimate excludes some overstay 
groups and may thus understate the extent of the total overstay 
problem. The main overstay groups omitted from the DHS overstay 
estimate of 2.3 million are:

* long-term Mexican and Canadian overstays who were not required to 
fill out Form I-94 at entry and:

* short-term overstays, whether from Mexico, Canada, or other 
countries.

Short-term overstays cannot be ignored because, as we explain in a 
later section, some terrorists or terrorist supporters are in this 
group.[Footnote 16]

A Substantial Proportion of Illegal Immigrants Are Overstays:

DHS's overstay estimate for January 2000 (that is, that overstays 
represent one-third of the illegal immigrant population, or 2.3 million 
residents) was based, in part, on a projection forward of overstay 
rates for 1992. Earlier, we identified challenges and potential 
weaknesses in Immigration and Naturalization Service (INS) procedures 
used in estimating these overstays (including an incorrect INS 
formula).[Footnote 17] Therefore, we sought alternative, and more 
current, data sources.

The first alternative data source we identified is a survey that DHS 
and the National Institute of Child Health and Human Development 
sponsored, in partnership with other federal agencies.[Footnote 18] As 
reported in 2002, the survey (1) sampled more than 1,000 adult green-
card holders, (2) asked them about their prior immigration status, and 
(3) found that more than 300 self-reported earlier illegal status. The 
computer run we requested showed that 31 percent of these former 
illegals said they had been overstays. (Most others reported prior 
illegal border crossing.)[Footnote 19]

A second alternative source was a set of data we obtained from 
Operation Tarmac and other recent sweeps of employees who, in the 
course of their work, had access to sensitive areas in airports, other 
critical infrastructures, or special events (for example, the Super 
Bowl). Although investigators conducting these operations collected 
information on overstaying, they had not systematically recorded data 
for overstays versus illegal border crossers or other categories of 
illegal immigrants. We requested that DHS manually review case files 
for those arrested and identify the number who were overstays. DHS 
reported to us on a total of 917 arrests, taken from operations at a 
sample of Operation Tarmac airports and at all other critical 
infrastructure and special-event locations investigated. As we detail 
later in this report, 246 of the 917 cases--or 27 percent--were 
categorized as overstays.

Another source we obtained from DHS was similar information on an 
operation identifying illegal alien employees at a retail chain 
(unrelated to terrorist concerns). In this operation, 138 of 243 cases-
-that is, 57 percent--were identified as overstays.[Footnote 20]

The percentages above do not represent the illegal population but, as 
indicated above, do provide some evidence that in all likelihood, a 
substantial proportion of illegal immigrants are overstays.[Footnote 
21]

DHS's Estimate Excludes Major Overstay Groups:

The DHS overstay estimate appears to be an understatement for two main 
reasons. The first is that it is based on data from I-94 forms--and 
many Mexican and Canadian visitors are not required to complete this 
form.[Footnote 22] The second is that, by definition, the population of 
illegal immigrants does not include many short-term overstays.

Thus, DHS's 2.3 million estimate excludes the following overstay 
groups:

Mexican and Canadian visitors who did not fill out Form I-94 and who 
overstayed and settled here.[Footnote 23] (Although these long-term 
overstay settlers are included in DHS's estimate of 7 million illegal 
immigrants, they are, erroneously, categorized as illegal immigrants 
other than overstays. This is because DHS used I-94 data to estimate 
overstays.)[Footnote 24]

Visitors filling out Form I-94 who overstay for short periods of time.

Mexicans and Canadian visitors who do not fill out Form I-94 and who 
overstay for short periods of time.

The excluded groups are illustrated in figure 3, together with the 
overstay group that is covered.

Figure 3: Key Groups Covered and Not Covered by DHS's Overstay 
Estimate:

[See PDF for image]

[A] During fiscal year 2001, nearly 33 million visits were tracked by 
I-94 arrival forms. Of these tracked visits, 14 percent (about 4.6 
million) were by Mexican and Canadian citizens.

[B] Aliens not tracked were mainly Canadian citizens or Mexican holders 
of BCCs issued by the Department of State. During fiscal years 1999 to 
2003, the Department of State issued 6.4 million Mexican BCCs. 
According to unofficial DHS planning figures for fiscal year 2002, 
approximately 156 million "inspections [were] conducted" for visits by 
visa-exempt aliens and aliens with Mexican BCCs at land border 
crossings. (See Department of Homeland Security, US-VISIT Program 
Overview (Washington, D.C.: Sept. 16, 2003).) DHS's Office of 
Immigration Statistics told us that the Form I-94 system tracks very 
few such visits. Because some persons may visit the United States 
repeatedly, the number of persons inspected is less than the number of 
inspections.

[End of figure]

As a result, an overstay settler group is omitted from DHS's overstay 
estimate (that is, from DHS's estimate that one-third of the illegal 
immigrant population, or 2.3 million, are overstays). The Mexican-
Canadian overstay group at issue was apparently included in the 7 
million--but not the 2.3 million--estimate.[Footnote 25] It is not 
clear whether this issue may affect some of the three "rough-check" 
comparison figures cited above.[Footnote 26]

DHS's procedures for arriving at the estimate of 7 million are heavily 
based on the 2000 census and include those who settled here, were 
residing here at the time of the 2000 census, and were included either 
in the actual census count or in corrections for possible 
undercounts.[Footnote 27] The census is not likely to include aliens 
illegally present for relatively short periods of time, in part because 
such persons may not identify the United States as their principal 
place of residence. Consistent with this, when using I-94 data to 
estimate overstays, DHS specifically excluded short-term overstays. 
This is important because overstaying is not limited to those who 
illegally immigrate here and intend to remain for years. Many others 
overstay for only a few days, weeks, or months, including those 
discussed above who are--and are not--required to fill out Form I-94.

Finally, we note two possible further limitations: DHS overstay 
estimates do not address either the issue of "prior overstays" or 
possible trends in overstaying:

* As indicated by the survey cited above (our first alternative data 
source), a portion of overstays who settle here eventually obtain legal 
status. Many prior overstays appear to be residing legally in the 
United States now, and thus the "flow" of overstays who settle here may 
be larger than a net estimate of the overstay population at a single 
point in time implies.

* DHS estimated overstays using I-94 data from the early 1990s, and it 
projected those estimates forward to January 2000. Without independent 
overstay estimates for two points in time, a reliable assessment of 
change is not possible. DHS has not published estimates for more recent 
dates--that is, since January 2000.

Overstay trend estimates would be of interest but are not available. 
Visits to the United States decreased somewhat in 2002. Data from the 
Bureau of the Census indicate that the overall trend of the foreign-
born population (of whom the majority are legal) was to steadily 
increase in size from 1990 through 2003. (See fig. 4.)

Figure 4: Change in the Size of the Foreign-Born Population, 1990-2003:

[See PDF for image]

Note: CPS refers to the Current Population Survey. According to the 
Census Bureau, the apparently sharp increase between 1999 and 2000 
likely reflects (1) some real growth in the foreign-born population 
during that single year, (2) growth in the foreign-born population that 
occurred earlier in the decade but was not fully detected until the 
2000 census, and (3) differences in decennial census coverage (1990 
versus 2000) and related CPS weighting procedures.

[End of figure]

Unresolved Tracking System Weaknesses Heighten the Overstay Problem:

We recognize that an overstay tracking system is only one ingredient in 
effective overstay control and enforcement. However, we believe it is a 
crucial ingredient. Without an adequate overstay tracking system, an 
accurate list of overstays cannot be generated for control purposes. In 
earlier reports, we identified a variety of weaknesses in the I-94 
overstay tracking system. DHS has begun to phase in US-VISIT--a new 
program for collecting, maintaining, and sharing information on foreign 
nationals.

I-94 Tracking System Weaknesses Limit Control Options:

We discussed above one weakness in DHS's Form I-94 overstay tracking 
system--its limited coverage of Mexican and Canadian visitors. In our 
previous work, we have pointed to at least three other weaknesses:

* Failure to update the visitor's authorized period of admission or 
immigration status. Last year, we reported that DHS does not 
"consistently enter change of status data . . . [or] integrate these 
data with those for entry and departure."[Footnote 28] DHS told us that 
linkage to obtain updated information may occur for an individual, as 
when a consular official updates information on an earlier period of 
admission for someone seeking a new visa, but DHS acknowledged that 
linkage cannot be achieved broadly to yield an accurate list of 
visitors who overstayed.

* Lack of reliable address information and inability to locate 
visitors. Some visitors do not fill in destination address information 
on Form I-94 or they do so inadequately. A related issue that we 
reported in 2002 is DHS's inability to obtain updated address 
information during each visitor's stay. Such information could be a 
valuable addition to the arrival, departure, and destination address 
information that is collected.[Footnote 29]

* Missing departure forms. We reported in 1995 that "airlines are 
responsible for collecting . . . departure forms when visitors leave 
[by air]

. . . . But for some visitors who may have actually left the United 
States [there is no] record of the departures."[Footnote 30] DHS 
acknowledges that this is still a concern, the situation is analogous 
for cruise lines, and noncollection is a larger problem for land exits.

Our recent work has also drawn attention to identity fraud, 
demonstrating how persons presenting fraudulent documents (bearing a 
name other than their own) to DHS inspectors could enter the United 
States.[Footnote 31] Visitors whose fraudulent documents pass 
inspection could record a name other than their own on Form I-94.

In our current work, we have identified two further weaknesses in the 
overstay tracking system. One weakness is the inability to match some 
departure forms back to corresponding arrival forms. DHS has suggested 
that when a visitor loses the original departure form, matching is less 
certain because it can no longer be based on identical numbers printed 
on the top and bottom halves of the original form. The other weakness 
is that at land ports (and possibly airports and seaports), the 
collection of departure forms is vulnerable to manipulation--in other 
words, visitors could make it appear that they had left when they had 
not. To illustrate, on bridges where toll collectors accept Form I-94 
at the southwestern border, a person departing the United States by 
land could hand in someone else's form.

Because of these weaknesses, DHS has no accurate list of overstays to 
send to consular officials or DHS inspectors. This limits DHS's ability 
to consider past overstaying when issuing new visas or allowing 
visitors to reenter. More generally, the lack of an accurate list 
limits prevention and enforcement. For example, accurate data on 
overstays and other visitors might help define patterns for better 
differentiating visa applicants with higher overstay risk. And without 
an accurate list and updated addresses, it is not possible to identify 
and locate new overstays to remind them of penalties for not departing. 
Such efforts fall under the category of interior enforcement. As we 
previously reported, "historically . . . over five times more resources 
in terms of staff and budget [have been devoted to] border enforcement 
than . . . [to] interior enforcement."[Footnote 32]

Despite large numbers of overstays, current efforts to deport them are 
generally limited to (1) criminals and smugglers, (2) employees 
identified as illegal workers at airports and other critical 
infrastructure locations, and (3) persons included in special control 
efforts such as the 2003 domestic registration (or "call in" component) 
of the NSEERS program (the National Security Entry and Exit 
Registration System).[Footnote 33] DHS statisticians told us that for 
fiscal year 2002, the risk of arrest for all overstays was less than 2 
percent.[Footnote 34] For most other overstays (that is, for persons 
not in targeted groups), the risk of deportation is considerably lower. 
DHS told us that because of limited resources, it has focused 
enforcement on high-priority illegal alien groups.

The effect that weaknesses in the overstay tracking system has on 
overstay data is illustrated by the inaccurate--and, according to DHS, 
inflated--lists of what it has termed "apparent overstays." For fiscal 
year 2001 arrivals, the system yielded:

* a list of 6.5 million "apparent overstays" for which DHS had no 
departure record that matched the arrivals and:

* an additional list of a half million other visits that ended after 
the visitors' initial periods of admission expired.

(For data on specific countries or country groups, see app. V, table 
5.)

However, DHS has no way of knowing which of these are real cases of 
overstaying and which are false, because in all likelihood, some of 
these visitors departed or legally changed their status--or legally 
extended their periods of admission.

In the past, we made a number of recommendations that directly or 
indirectly addressed some of these system weaknesses, but these 
recommendations have not been implemented or have been only partially 
implemented. (Of these, four key recommendations are reproduced in app. 
VI.)

DHS Intends Its New Tracking Initiatives to Address System Weaknesses, 
but Issues Remain:

Two recent DHS programs are aimed at remedying some of the weaknesses 
we have discussed.[Footnote 35] First, as part of NSEERS, an effort is 
being made to register certain visitors at points of entry (POE) to the 
United States and to have government inspectors register departures. 
But that POE effort does not cover most visitors and does not involve 
inspectors' actually observing departures.[Footnote 36]

Second, US-VISIT is DHS's new program for collecting, maintaining, and 
sharing information on foreign nationals who enter the United 
States.[Footnote 37] Among other things, the first phase of US-VISIT is 
designed to:

* collect electronic entry-exit passenger and crew manifest data and to 
match entry and exit data to each other (based on passengers' 
biographic information) and to other information, thus identifying 
overstays, and:

* use biometrics to verify foreign visitors' identities, upon entry, at 
115 airports and 14 seaports of entry.

We have reported elsewhere that this first phase is operational but 
that improvements are needed. Three additional phases are planned that 
would extend US-VISIT's identity-verification capabilities--initially, 
to high-traffic land borders and, eventually, to all remaining ports of 
entry--as well as adding capabilities, such as that of processing 
machine-readable documents that use biometric identifiers.[Footnote 
38] DHS told us that a current goal is to incorporate NSEERS POE into 
the US-VISIT program.

Successfully designing--and implementing--US-VISIT involves a number 
of challenges. For example, DHS concurred with recommendations in our 
2003 report, including, among other things, that DHS develop key 
acquisition management controls.[Footnote 39] As we have reported 
elsewhere, US-VISIT has not yet developed a strategy for defining and 
implementing these controls or a time period for doing so.[Footnote 40]

Other crucial issues are whether US-VISIT can avoid weaknesses 
associated with the Form I-94 system. Some challenges--such as 
implementing an appropriate system at land borders, obtaining accurate 
addresses, verifying the identity of all entering visitors, and 
otherwise insuring the integrity of the inspections process--may be 
very difficult to overcome.[Footnote 41]

While the design and implementation of US-VISIT face a number of 
challenges, we believe that it might be useful to determine whether the 
new program successfully avoids specific weaknesses associated with the 
long-standing I-94 system. Together with other efforts, this might help 
identify some difficult challenges in advance and enhance US-VISIT's 
chances for eventual success as an overstay tracking system.

Overstay Issues May Complicate Efforts to Ensure Domestic Security:

Tracking System Weaknesses Encourage Overstays and Hamper Some 
Counterterrorism Efforts:

Weaknesses in overstay tracking may encourage visitors and potential 
terrorists who legally enter the United States to overstay. Once here, 
terrorists may overstay or use other stratagems to extend their stay--
such as exiting and reentering (to obtain a new authorized period of 
admission) or applying for a change of status. As shown in table 1, of 
the six hijackers who actually flew the planes on September 11 or were 
apparent leaders, three were out of status on or before September 11--
two because of prior short-term overstaying.

Table 1: Overstay and Other Immigration Status Data on September 11 
Hijackers:

Hijacker group: 6 who actually flew the planes[A] or were apparent 
leaders; 
Immigration status issue: 2 prior overstays[B], 1 out-of-status 
student[C]; 
Entries: 18 total (1 to 7 entries each); 
Change-of-status applications: 3.

Hijacker group: 13 other hijackers; 
Immigration status issue: 2 overstays; 
Entries: 13 total (1 each); 
Change-of-status applications: 0.

Hijacker group: Total = 19 hijackers; 
Immigration status issue: 4 overstays total; 
5 violations (including overstays and the out-of-status student); 
Entries: 31 total (from 1 to 7 entries each); 
Change-of-status applications: 3 total; (0 to 1 each). 

Sources: FBI for pilot and leader information; U.S. Department of 
Homeland Security and GAO analysis for immigration histories.

Note: An overstay is an illegal alien who was legally admitted to the 
United States for a specific authorized period but remained here after 
that period expired, without obtaining an extension or a change of 
status or meeting other specific conditions. Overstays who settle here 
are part of the illegal immigrant population.

[A] Acted as pilots or copilots. Three of the six both acted as pilots 
or copilots and were apparent leaders.

[B] The two prior overstays had remained in the United States beyond 
their authorized period of admission; they accrued days of overstay at 
that time.

[C] Violated terms of student visa by not attending school.

[End of table]

Additionally, a number of current or prior overstays were arrested 
after September 11 on charges related to terrorism. For example:

* Two overstays pled guilty to separate instances of identity document 
fraud and were connected to different hijackers in the September 11 
group. They were current, short-term overstays when the identity 
document fraud occurred.

* Four others with a history of overstaying (and variously connected to 
the September 11 hijackers, the Taliban, and Hezbollah terrorists) pled 
guilty to document fraud or weapons charges or were convicted of money 
laundering.[Footnote 42] One of these was also convicted of providing 
Hezbollah material support, including night vision devices and other 
weapons-related technology.[Footnote 43]

Last, the gunman who fired on several people at the El Al ticket 
counter of Los Angeles International Airport was identified (by DHS) as 
a prior overstay.

Terrorists who enter as legal visitors are hidden within the much 
larger populations of all legal visitors, overstays, and other illegals 
such as border crossers. Improved overstay tracking could help 
counterterrorism investigators and prosecutors locate suspicious 
individuals placed on watch lists after they entered the country. The 
director of the Foreign Terrorist Tracking Task Force told us that he 
considered overstay tracking data helpful. For example, these data--
together with additional analysis--can be important in quickly and 
efficiently determining whether suspected terrorists were in the United 
States at specific times.

As we reported in 2003, between "September 11 and November 9, 2001 
[that is, over the course of 2 months], . . . INS compiled a list of 
aliens whose characteristics were similar to those of the hijackers" in 
types of visas, countries issuing their passports, and dates of entry 
into the United States.[Footnote 44] While the list of aliens was part 
of an effort to identify and locate specific persons for interviews, it 
contained duplicate names and data entry errors. In other words, poor 
data hampered the government's efforts to obtain information in the 
wake of a national emergency, and it was necessary to turn to private 
sector information. Reporting earlier that INS data "could not be fully 
relied on to locate many aliens who were of interest to the United 
States," we had indicated that the Form I-94 system is relevant, 
stressing the need for improved change-of-address notification 
requirements.[Footnote 45] INS generally concurred with our 
recommendations.

Overstays' Employment with Access to Sensitive Areas May Affect 
Security:

DHS has declared that combating fraudulent employment at critical 
infrastructures, such as airports, is a priority for domestic 
security.[Footnote 46] DHS has ongoing efforts to identify illegal 
workers in jobs at various infrastructures (for example, airport 
workers with security badges). These sweeps are thought to reduce the 
nation's vulnerability to terrorism, because, as experts have told us, 
(1) security badges issued on the basis of fraudulent IDs constitute 
security breaches, and (2) overstays and other illegal aliens working 
in such facilities might be hesitant to report suspicious activities 
for fear of drawing authorities' attention to themselves or they might 
be vulnerable to compromise.

Operation Tarmac is a national multiagency initiative focused on 
screening employees working in secure areas of U.S. airports.[Footnote 
47] Post-September 11 investigations of passenger-screening companies 
and other secure-area employers revealed substantial numbers of 
unauthorized foreign national employees. As a result, further sweeps 
began in 2001 with Washington, D.C., and Salt Lake City (in preparation 
for the Winter Olympics); these eventually became known as Operation 
Tarmac and are still ongoing. As of April 2004, DHS reported that 195 
airports had been investigated and 5,877 businesses had been audited. 
Operation Tarmac investigators had checked the I-9 Employment 
Eligibility Verification forms or badging office records (or both) for 
about 385,000 employees and had found 4,918 unauthorized 
workers.[Footnote 48]

As we discussed earlier in this report, when we obtained data on the 
specific immigration status of workers who were arrested or scheduled 
for deportation at 26 Operation Tarmac airports, we found that a 
substantial number were overstays (see table 2).

Table 2: Operation Tarmac Data for Selected Airports: Number of 
Overstays Arrested by Airport:

Airport: Atlanta Hartsfield (ATL); 
Overstays: 14; 
Not overstays (EWIs and others)[A]: 4; 
Total unauthorized workers arrested: 18.

Airport: Austin (AUS); 
Overstays: 1; 
Not overstays (EWIs and others)[A]: 22; 
Total unauthorized workers arrested: 23.

Airport: Baltimore (BWI); 
Overstays: 3; 
Not overstays (EWIs and others)[A]: 0; 
Total unauthorized workers arrested: 3.

Airport: Boston Logan (BOS); 
Overstays: 6; 
Not overstays (EWIs and others)[A]: 14; 
Total unauthorized workers arrested: 20.

Airport: Burbank, California (BUR); 
Overstays: 5; 
Not overstays (EWIs and others)[A]: 5; 
Total unauthorized workers arrested: 10.

Airport: Chicago O'Hare (ORD) and Midway (MDW); 
Overstays: 10; 
Not overstays (EWIs and others)[A]: 28; 
Total unauthorized workers arrested: 38.

Airport: Dallas (DFW); 
Overstays: 26; 
Not overstays (EWIs and others)[A]: 41; 
Total unauthorized workers arrested: 67.

Airport: Denver (DIA); 
Overstays: 6; 
Not overstays (EWIs and others)[A]: 36; 
Total unauthorized workers arrested: 42.

Airport: Detroit (DTW); 
Overstays: 2; 
Not overstays (EWIs and others)[A]: 4; 
Total unauthorized workers arrested: 6.

Airport: Houston Bush (IAH); 
Overstays: 3; 
Not overstays (EWIs and others)[A]: 100; 
Total unauthorized workers arrested: 103.

Airport: Jacksonville (JAX); 
Overstays: 2; 
Not overstays (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 3.

Airport: Los Angeles (LAX); 
Overstays: 5; 
Not overstays (EWIs and others)[A]: 18; 
Total unauthorized workers arrested: 23.

Airport: Manchester, New Hampshire (MHT); 
Overstays: 3; 
Not overstays (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 4.

Airport: Newark, New Jersey (EWR); 
Overstays: 8; 
Not overstays (EWIs and others)[A]: 5; 
Total unauthorized workers arrested: 13.

Airport: New York JFK and La Guardia (LGA); 
Overstays: 11; 
Not overstays (EWIs and others)[A]: 15; 
Total unauthorized workers arrested: 26.

Airport: Omaha (OMA); 
Overstays: 0; 
Not overstays (EWIs and others)[A]: 9; 
Total unauthorized workers arrested: 9.

Airport: Orlando (MCO); 
Overstays: 12; 
Not overstays (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 13.

Airport: Phoenix Sky Harbor (PHX); 
Overstays: 7; 
Not overstays (EWIs and others)[A]: 21; 
Total unauthorized workers arrested: 28.

Airport: Salt Lake City, Utah (SLC); 
Overstays: 23; 
Not overstays (EWIs and others)[A]: 25; 
Total unauthorized workers arrested: 48.

Airport: San Francisco (SFO); 
Overstays: 4; 
Not overstays (EWIs and others)[A]: 13; 
Total unauthorized workers arrested: 17.

Airport: Sarasota (SRQ); 
Overstays: 1; 
Not overstays (EWIs and others)[A]: 6; 
Total unauthorized workers arrested: 7.

Airport: Tampa (TPA); 
Overstays: 10; 
Not overstays (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 11.

Airport: Washington Dulles (IAD); 
Overstays: 7; 
Not overstays (EWIs and others)[A]: 40; 
Total unauthorized workers arrested: 47.

Airport: Washington Reagan National (DCA); 
Overstays: 13; 
Not overstays (EWIs and others)[A]: 15; 
Total unauthorized workers arrested: 28.

Total number; 
Overstays: 182; 
Not overstays (EWIs and others)[A]: 425; 
Total unauthorized workers arrested: 607.

Percent; 
Overstays: 30.0%; 
Not overstays (EWIs and others)[A]: 70.0%; 
Total unauthorized workers arrested: 100.0%. 

Sources: U.S. Department of Homeland Security and GAO analysis.

Note: Data are for operations conducted from October 2001 through April 
2004.

[A] Entered without inspection (surreptitious border crosser).

[End of table]

Overstays had fraudulently gained access to the secure areas of all but 
one of the 26 airports reviewed. Of 607 unauthorized workers arrested 
at these airports, 182, or 30 percent, were overstays.[Footnote 49] Of 
these overstays, 19 percent were Mexican nationals and 38 percent were 
from other Latin American countries. A total of 10 unauthorized airport 
workers were arrested from special interest (NSEERS) countries, 5 of 
whom were overstays. (See app. VII for more complete Operation Tarmac 
nationality data.)

The illegal immigrant workers with access to secure airport areas were 
employed by airlines (for example, at Washington Dulles International 
Airport and Washington Reagan National Airport, these included 
American, Atlantic Coast, Delta, Northwest, and United Airlines, as 
well as SwissAir and British Airways) and by a variety of other 
companies (for example, Federal Express and Ogden Services). Job 
descriptions included, among others, aircraft maintenance technician, 
airline agent, airline cabin service attendant, airplane fueler, 
baggage handler, cargo operations manager, electrician, janitorial 
supervisor, member of a cleaning crew, predeparture screener, ramp 
agent, and skycap. One overstay was employed in an airport badging 
office.

Without fraud or counterfeit documents, illegal workers would not have 
been able to obtain these jobs and badges, allowing them access to 
secure areas.[Footnote 50] In the large majority of these cases, 
illegal immigrants had misused Social Security numbers and identity 
documents to illegally obtain airport jobs and security 
badges.[Footnote 51] A much smaller number of airport employees had 
misrepresented their criminal histories in order to obtain their jobs 
and badges.[Footnote 52] One DHS official emphasized that these were 
all serious security breaches because there was no way to know who 
these people actually were. Moreover, another DHS official told us that 
Operation Tarmac is likely not to have identified all illegal aliens 
working in secure areas of airports. Of the 4,918 unauthorized workers 
identified, 1,054 have been arrested, and the 3,864 others have left 
their airport jobs and eluded arrest.

Sweeps similar to Operation Tarmac were subsequently initiated for a 
broad range of critical infrastructure components and special events, 
such as the Super Bowl (see table 3).

Table 3: Critical Infrastructure and Special-Event Operations: Data on 
Number of Overstays Arrested by Operation:

Operation: Big John (JFK carrier refitting shipyard); 
Overstays: 1; 
Not overstays: (EWIs and others)[A]: 32; 
Total unauthorized workers arrested: 33.

Operation: Deny Access San Diego (shipyards); 
Overstays: 1; 
Not overstays: (EWIs and others)[A]: 15; 
Total unauthorized workers arrested: 16.

Operation: Ensure West (Lawrence, Berkeley, and Livermore); 
Overstays: 0; 
Not overstays: (EWIs and others)[A]: 3; 
Total unauthorized workers arrested: 3.

Operation: Federal Protective Service (DC); 
Overstays: 2; 
Not overstays: (EWIs and others)[A]: 0; 
Total unauthorized workers arrested: 2.

Operation: Federal Protective Service (San Francisco); 
Overstays: 0; 
Not overstays: (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 1.

Operation: Fort Dix/McGuire (New Jersey); 
Overstays: 9; 
Not overstays: (EWIs and others)[A]: 7; 
Total unauthorized workers arrested: 16.

Operation: Game Day (San Diego Super Bowl); 
Overstays: 8; 
Not overstays: (EWIs and others)[A]: 71; 
Total unauthorized workers arrested: 79.

Operation: Glow Worm (nuclear power plants); 
Overstays: 0; 
Not overstays: (EWIs and others)[A]: 1; 
Total unauthorized workers arrested: 1.

Operation: Hub Cap LA (taxi drivers); 
Overstays: 22; 
Not overstays: (EWIs and others)[A]: 13; 
Total unauthorized workers arrested: 35.

Operation: Kurburdis (Air Force Academy); 
Overstays: 2; 
Not overstays: (EWIs and others)[A]: 33; 
Total unauthorized workers arrested: 35.

Operation: Pipe Line (Alaska); 
Overstays: 0; 
Not overstays: (EWIs and others)[A]: 3; 
Total unauthorized workers arrested: 3.

Operation: Security Breach II (Miami port); 
Overstays: 1; 
Not overstays: (EWIs and others)[A]: 7; 
Total unauthorized workers arrested: 8.

Operation: Sensitive national landmarks[B]; 
Overstays: 9; 
Not overstays: (EWIs and others)[A]: 16; 
Total unauthorized workers arrested: 25.

Operation: Sikorsky (Hartford, Connecticut); 
Overstays: 7; 
Not overstays: (EWIs and others)[A]: 10; 
Total unauthorized workers arrested: 17.

Operation: Warren AFB (Colorado); 
Overstays: 0; 
Not overstays: (EWIs and others)[A]: 31; 
Total unauthorized workers arrested: 31.

Operation: Woodworker (Fort Leonard Wood); 
Overstays: 2; 
Not overstays: (EWIs and others)[A]: 3; 
Total unauthorized workers arrested: 5.

Operation: Total number: Critical infrastructure and special-event 
operations; 
Overstays: 64; 
Not overstays: (EWIs and others)[A]: 246; 
Total unauthorized workers arrested: 310.

Percent; 
Overstays: 20.7%; 
Not overstays: (EWIs and others)[A]: 79.4%; 
Total unauthorized workers arrested: 100.0%.

Operation: Overall total number: Selected Tarmac airports and critical 
infrastructure and special-event locations; 
Overstays: 246; 
Not overstays: (EWIs and others)[A]: 671; 
Total unauthorized workers arrested: 917.

Percent; 
Overstays: 26.8%; 
Not overstays: (EWIs and others)[A]: 73.2%; 
Total unauthorized workers arrested: 100.0%. 

Sources: U.S. Department of Homeland Security and GAO analysis.

Note: Data are for operations beginning in 2002 and conducted through 
April 2004.

[A] Entered without inspection (surreptitious border crosser).

[B] Refers to multiple locations; landmark names are not specified for 
security reasons.

[End of table]

The employees checked in these sweeps ranged from workers at nuclear 
power plants, military bases, pipelines, and special national events 
such as the Super Bowl to security officers for the Federal Protective 
Services, which guards federal buildings, and workers at sensitive 
national landmarks. Illegal immigrants committing identity fraud were 
found to be working at every one of these locations. Overstays were 
found to be working at two-thirds of these facilities and represented 
20.7 percent of the unauthorized workers found by investigators of 
critical infrastructure sites.

We asked DHS Immigration and Customs Enforcement (ICE) officials why 
there were more than 4,900 security breaches at airports, most of which 
involved illegal aliens. They stated that airport badging authorities 
did not routinely make rigorous checks.[Footnote 53] They stated that 
while badging authorities were able to check the FBI databases for 
criminal histories and terrorists on watch lists, they had no protocol 
for checking Social Security numbers and only a limited ability to 
verify immigration status.[Footnote 54] In contrast, Operation Tarmac 
and related critical infrastructure sweeps were joint federal 
operations that were able to do more rigorous, but still limited, 
checks because they had full access to DHS and Social Security 
Administration (SSA) data.

We asked if this problem had been corrected as a result of Operation 
Tarmac. DHS officials stated that it had not. They stated that airport 
badging authorities still could not make these positive identification 
checks. They stated that, in effect, the airports knew who was not 
working there (that is, airports had checked for known terrorists and 
criminals) but not who was. Officials we interviewed from the 
Department of Transportation's (DOT) Inspector General's office and the 
U.S. Attorney's office have also expressed their concern about this 
problem.

With respect to the other security breaches at critical infrastructure 
sites, DHS officials told us that in many cases, the situation was 
similar to that described for airport badging authorities.

Last, officials from the Transportation Security Administration (TSA) 
recently testified before the House Aviation subcommittee that persons 
employed at airports will not be subject to the CAPPS II screening that 
airline passengers will undergo--and are not now subject to physical 
screening--because TSA relies on employees' rigorous background checks 
instead. It differs by airport, but the legislative requirement is that 
workers must be screened, and TSA policy is that screening can consist 
of background checks and credentialing procedures rather than physical 
screening.[Footnote 55]

Operation Tarmac found airport background checks to have failed more 
than 4,900 times. Not all were overstays, but overstays do represent a 
substantial portion of the cases in which badged, unauthorized 
employees were identified.

Conclusion:

In the area of illegal immigration, reliable information remains 
elusive. Yet it is clear that the level of overstaying is significant 
and that the Form I-94 overstay tracking system contains important 
weaknesses. While we cannot quantify the risk to domestic security, we 
believe that efforts to ensure domestic security are affected to some 
degree by the level of overstaying that apparently occurs and by 
limitations in overstay tracking. This is illustrated by the employment 
of overstays at critical infrastructure locations.

DHS recently initiated two efforts to develop improved systems, but 
challenges remain. Designing and implementing a viable and effective 
overstay tracking system is an important priority, not only because of 
its potential consequences for policy effectiveness but also because it 
could contribute to broader overstay control and enforcement efforts--
and because it could enhance a layered defense.

Agency Comments:

We provided a draft of this report to the Department of Homeland 
Security and the Department of Justice. Both agencies informed us that 
they had no comments.

As agreed with your office, we plan no distribution of this report 
until 21 days after its issue date, unless you publicly announce its 
contents earlier. We will then send copies to the Secretary of the 
Department of Homeland Security, the Attorney General, appropriate 
congressional committees, and others who are interested. The report is 
also available at no charge on GAO's Web site at http://www.gao.gov.

If you or your staff would like to discuss any of the issues we present 
here, please call me at 202-512-2700 or Judith Droitcour, who served as 
project director on this study, at 202-512-9145. Other individuals who 
made key contributions to this report are Daniel Rodriguez, Eric M. 
Larson, Andrea Miller, and Mona Sehgal.

Sincerely yours,

Signed by: 

Nancy R. Kingsbury, Managing Director: 
Applied Research and Methods:

[End of section]

Appendix I: Copy of Form I-94:

Figure 5: Form I-94:

[See PDF for image]

[End of figure]

[End of section]

Appendix II: Perimeter for Mexican Visitors Not Required to Complete 
Form I-94:

Mexicans entering the United States with a border crossing card at the 
southwestern border who intend to limit their stay to 72 hours or less 
are not required to obtain a visa or to complete Form I-94 if they 
limit their travel to within a perimeter that is generally 25 miles 
from the border but that may extend up to 75 miles in Arizona 
(illustrated in fig. 6).

Figure 6: Perimeter for Mexican Visitors Not Required to Complete Form 
I-94:

[See PDF for image]

[End of figure]

[End of section]

Appendix III: How DHS Estimated Illegal Immigrants:

DHS's estimate of 7 million illegal U.S. residents as of January 2000 
is based on the separate calculation of two estimates: (1) about 5.5 
million illegal residents who arrived in the United States between 1990 
and 2000 and were residing here, in illegal status, as of January 2000 
and (2) about 1.5 million other illegal residents who arrived before 
1990 and were here in illegal status as of January 2000.[Footnote 56] 
Because this estimate focuses on resident aliens, many aliens here for 
short periods (for example, 3 to 9 months) were likely to be 
excluded.[Footnote 57]

The first component estimate--the estimate of 5.5 million here 
illegally as of January 2000 who arrived between 1990 and 2000--was 
derived through a "residual," or subtraction, method. Using data from 
the decennial census (long form), DHS estimated the number of total 
foreign-born noncitizens residing here as of January 2000 who had 
arrived in each year from 1990 up to 2000.[Footnote 58]

From this, DHS subtracted an estimate of legally resident foreign-born 
noncitizens, based on annual DHS administrative data--for example, the 
number of green cards issued each year, adjusted downward to account 
for deaths and return migration. Also subtracted were an estimate of 
the number of (1) residents who had applied for and would eventually 
receive legal status (estimated at 200,000) and (2) asylees, parolees, 
and persons with temporary protected status (TPS) who had received work 
authorization but not permanent resident status (377,000).[Footnote 59]

These subtraction procedures yielded a "residual" estimate of illegal 
residents. The actual subtraction was conducted separately for each 
year. In this estimation process, DHS adjusted for various factors, 
such as census undercounts.[Footnote 60]

According to the INS paper presenting the estimate of 7 million, the 
second component in this estimate--the estimate of 1.5 million illegal 
residents who had arrived before 1990--was derived from:

* an estimate of 3.5 million illegal residents here in January 
1990[Footnote 61] and:

* DHS's estimate that, of the 3.5 million, 1.5 million had survived and 
remained here until 2000--without adjusting to legal status.[Footnote 
62]

To derive estimates for various countries or regions of origin (for 
example, Mexico or Asia), these procedures were carried out separately 
for 75 countries and for each region of origin.[Footnote 63]

The component estimate of 5.5 million illegal residents who arrived in 
the past decade is based on residual estimation, which is a generally 
accepted demographic procedure; DHS also attempts to compensate for 
potential weaknesses in the source data--for example, compensating for 
some illegal immigrants' avoidance of the decennial census.

The other (second) component estimate--1.5 million illegal residents 
who had arrived before 1990--is based, in part, on the estimate of 3.5 
million illegal residents (as of 1990). The methods and procedures used 
to make the 3.5 million estimate have not been described in any DHS 
publication. However, the 3.5 million estimate can be compared with 
another published estimate of the illegal immigrant population, derived 
from residual-based estimates, calculated with data from the 1990 
census: 3.5 million for 1990.[Footnote 64] We have not evaluated this 
other published estimate; however, it is based on the generally 
accepted residual approach and was prepared by an expert in immigration 
statistics.[Footnote 65]

[End of section]

Appendix IV: How DHS Estimated Overstays:

DHS estimates that overstays constituted one-third of 7 million illegal 
immigrants residing in the United States as of January 2000.[Footnote 
66] DHS's one-third estimate is the result of a series of estimation 
procedures, described in this appendix.

In 1994, INS published estimates of overstays for October 1992, using 
data from the Form I-94 overstay tracking system we describe in this 
report. The overstay tracking system generally does not include Mexican 
visitors entering the United States with a BCC at the Southwest land 
border who state that their intention is to limit their stay to 72 
hours and not to travel beyond a set perimeter, generally 25 miles from 
the border. (See fig. 6.)[Footnote 67] The overstay tracking system 
also does not monitor Canadians admitted for up to 6 months, and there 
is no perimeter restriction for them. Such visitors who overstayed 
would not be included in an overstay estimate based on the I-94 data. 
Thus, from the very start, INS excluded some Mexican and Canadian 
overstays from its estimate.

In using the I-94 data, INS recognized that many departure forms were 
missing (even when visitors had actually departed). Therefore, INS 
devised a way to estimate this missing-data factor, which was termed 
"system error." As we explained in an earlier report.

* INS first identified as "index" countries those whose citizens were 
very unlikely to immigrate illegally to the United States--Sweden and 
Switzerland, among others.[Footnote 68] Then, using I-94 index-country 
data for a specific time period (that is, all index-country arrivals in 
a specific year, checked about 9 months after their initially required 
departure date), INS calculated the percentage of visitors from each 
index country who were "apparent overstays"--visitors for whom no 
matching record of departure could be found. Averaging this percentage 
across 12 index countries yielded a percentage figure (for example, 8 
percent). Assuming that virtually no visitors from those 12 countries 
actually overstayed, INS took its calculated percentage (for example, 8 
percent), plus a small margin of error, to represent a global level of 
"system error."

* INS then calculated the percentage of apparent overstays for each 
nonindex country--Korea, Mexico, Poland, and so on--as of October 1992. 
From a particular country's percentage of apparent overstays (for 
example, 12 percent), INS subtracted its global system error estimate 
(10 percent), yielding an estimated overstay rate for that country (for 
example, 2 percent). Any overstaying above the global "system error" 
was taken as an overstay flow estimate. Multiplied by the number of 
arrivals from a specific country in the designated year, this yielded 
the number of new overstays from that country.

Estimation was limited to overstays remaining here for about a year or 
more.

These data and procedures are the basis for all subsequent DHS overstay 
estimates. In our earlier report, we indicated a number of reasons why 
these overstay estimation procedures needed improvement.[Footnote 69]

INS combined these estimates with estimates for total illegal 
residents--to address the question of what percentage of total illegal 
alien residents overstays represented as of October 1992. Importantly, 
this step was carried out separately for 99 countries, with the 
remaining countries grouped together in their respective continents of 
origin--for example, the rest of Asia.[Footnote 70]

INS then applied the country-by-country October 1992 overstay 
percentages to project a later, October 1996 overstay estimate. 
Assuming no change between 1992 and 1996 in percentages of illegals 
estimated to be overstays in each country, INS multiplied the 1992 
overstay percentages by newly estimated (1996) per-country estimates of 
numbers of total illegal immigrants.

The same procedures (based on 1992 data) were carried out to yield 
country-by-country overstay estimates for January 2000. Summing the 
results across all country categories yielded an estimate of overstays-
-2.3 million, or one-third of all illegal aliens residing here as of 
January 2000.[Footnote 71]

Although we believe that the DHS estimation procedures contain several 
weak points, we were able to identify or develop three small-sample 
comparisons of illegal immigrants, as detailed in this report. These 
three "rough checks" indicated varying results--that 27 percent, 31 
percent, and 57 percent of the illegal immigrants "sampled" were 
overstays. But taken together, they clearly suggest that some 
substantial percentage of illegal residents are overstays.

With respect to possible trends, we do not believe that a reliable 
estimate of change in the overstay population can be based on DHS 
estimates. The estimate of overstays for 2000 is not based on any new 
overstay data; rather, it is based on (1) new data on the "total 
illegal population" as of January 2000 and (2) old data on what 
percentage of immigrants from each country or continent of origin are 
overstays. This means that we cannot identify two independent overstay 
estimates for the early 1990s and 2000.

[End of section]

Appendix V: DHS I-94 Data, Mixing Real and False Cases, Fiscal Year 
2001:

The weaknesses of DHS's I-94 data system--that is, the reasons why 
false cases of overstaying are mixed with real cases--are discussed in 
the report. Tables 4 and 5 illustrate the resulting data.

Table 4: DHS Classification of Apparent Overstays (A Mix of Real and 
False Cases) from I-94 Data by Arrival Mode, Fiscal Year 2001:

Mode of arrival: Air and sea; 
Arrived fiscal year 2001[A]: 29,688,000 (100%); 
Percentage DHS classified as: 
Departed before authorized stay expired: 84%; 
Percentage DHS classified as: 
Apparent overstays: No matching departure record[B]: 15%; 
Percentage DHS classified as: 
Apparent overstays: Records shows departure after initial stay 
expired[C]: 1%.

Mode of arrival: Land; 
Arrived fiscal year 2001[A]: 3,109,000 (100%); 
Percentage DHS classified as: 
Departed before authorized stay expired: 22%; 
Percentage DHS classified as: 
Apparent overstays: No matching departure record[B]: 71%; 
Percentage DHS classified as: 
Apparent overstays: Records shows departure after initial stay 
expired[C]: 7%.

Mode of arrival: All modes; 
Arrived fiscal year 2001[A]: 32,799,000 (100%); 
Percentage DHS classified as: 
Departed before authorized stay expired: 79%; 
Percentage DHS classified as: 
Apparent overstays: No matching departure record[B]: 20%; 
Percentage DHS classified as: 
Apparent overstays: Records shows departure after initial stay 
expired[C]: 1%.

Sources: U.S. Department of Homeland Security, Office of Immigration 
Statistics, and GAO analysis.

Note: To read the table, note that, for example, land arrivals (row 2) 
were recorded to number 3,109,000 in fiscal year 2001 and, of these, 22
 percent were recorded to have departed before their authorized stay 
expired; 71 percent had missing (or unmatched) departure records; and 
for 7 percent, the identified departure record indicated an actual date 
of departure after the initial date set for a required departure. The 
table includes visitors' arrivals from October 2000 through September 
2001 and their departures through January and February 2002. Arrival 
data represent arrivals rather than the number of visitors who arrived-
-that is, the data do not correct for multiple entries, and possibly 
multiple exits, by the same person. Figures may not sum because of 
rounding and because "all modes" includes some visits for which the 
mode of arrival is not known.

[A] Excludes many Mexicans and Canadians who, visiting for business or 
pleasure, are exempt from Form I-94 procedures.

[B] Includes cases in which no departure form could be matched to the 
arrival form--including some departing visitors who had lost their 
departure forms and filled out another form that could not be matched 
to their arrival form.

[C] The identified departure record indicates a departure date after 
the initially required time of departure. Includes some departing 
visitors who extended their stay or adjusted their status.

[End of table]

Table 5: DHS's Classification of Apparent Overstays (A Mix of Real and 
False Cases) from I-94 Data by Arrival Mode and Citizenship, Fiscal 
Year 2001:

Citizenship country or group: Mexico[C]; 
Air and sea arrivals: Arrived fiscal year 2001: 1,851,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 75%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 24%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 2,482,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 17%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 74%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 9%.

Citizenship country or group: Canada[C]; 
Air and sea arrivals: Arrived fiscal year 2001: 138,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 67%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 32%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 109,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 60%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 38%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 2.

Citizenship country or group: Countries in visa waiver program[D]; 
Air and sea arrivals: Arrived fiscal year 2001: 17,300,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 89%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 11%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 0%; 
Land arrivals: Arrived fiscal year 2001: 303,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 31%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 68%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%.

Citizenship country or group: Countries in 2003 NSEERS domestic 
registration program[E]; 
Air and sea arrivals: Arrived fiscal year 2001: 530,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 80%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 19%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 19,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 34%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 65%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%.

Citizenship country or group: Rest of world[F]; 
Air and sea arrivals: Arrived fiscal year 2001: 9,869,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 81%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 18%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 196,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 31%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 67%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 2%.

Citizenship country or group: Rest of Western Hemisphere; 
Air and sea arrivals: Arrived fiscal year 2001: 5,242,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 79%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 20%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 49,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 34%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 61%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 5%.

Citizenship country or group: Rest of Asia and Oceania; 
Air and sea arrivals: Arrived fiscal year 2001: 3,398,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 84%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 14%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 2%; 
Land arrivals: Arrived fiscal year 2001: 110,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 31%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 68%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%.

Citizenship country or group: Rest of Africa; 
Air and sea arrivals: Arrived fiscal year 2001: 347,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 78%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 21%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 6,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 36%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 63%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%.

Citizenship country or group: Rest of Europe; 
Air and sea arrivals: Arrived fiscal year 2001: 741,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 81%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 17%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 2%; 
Land arrivals: Arrived fiscal year 2001: 22,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 26%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 73%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%.

Citizenship country or group: Other, unknown; 
Air and sea arrivals: Arrived fiscal year 2001: 141,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 79%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 20%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 9,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 21%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 74%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 5%.

Citizenship country or group: Total; 
Air and sea arrivals: Arrived fiscal year 2001: 29,688,000 (100%); 
Air and sea arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 84%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 15%; 
Air and sea arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 1%; 
Land arrivals: Arrived fiscal year 2001: 3,109,000 (100%); 
Land arrivals: Percentage DHS classified as: 
Departed before authorized stay expired: 22%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: No matching departure record[A]: 71%; 
Land arrivals: Percentage DHS classified as: 
Apparent overstays: Departed after initial stay expired[B]: 7%.

Sources: U.S. Department of Homeland Security, Office of Immigration 
Statistics, and GAO analysis.

Note: Table includes visitors' arrivals October 2000 through September 
2001 and their departures through January and February 2002. Arrival 
data represent arrivals rather than the number of visitors who arrived-
-that is, the data do not correct for multiple entries, and possibly 
multiple exits, by the same person.

[A] Includes cases in which no departure form could be matched to the 
arrival form, including some departing visitors who had lost their 
departure forms and filled out another form that could not be matched 
to their arrival form.

[B] The departure record indicates a departure date after the initially 
required time of departure. This includes some departing visitors who 
had extended their stay or adjusted their status.

[C] Excludes Mexicans or Canadians visiting for business or pleasure 
and exempt from Form I-94 procedures.

[D] Most, but not all, visitors from Permanent Visa Waiver countries 
enter under this program. Visa waiver countries in this tally are 
Andorra, Australia, Austria, Belgium, Brunei, Denmark, Finland, France, 
Germany, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, 
Monaco, the Netherlands, New Zealand, Norway, Portugal, San Marino, 
Singapore, Slovenia, Spain, Sweden, Switzerland, and the United 
Kingdom. (Excludes Argentina and Uruguay, which were visa waiver 
countries in fiscal year 2001.)

[E] The 25 countries in the NSEERS 2003 domestic registration program 
include (1) 8 countries also subject to point-of-entry (POE) 
registration (Iran, Iraq, Libya, Pakistan, Saudi Arabia, Sudan, Syria, 
and Yemen) and (2) 17 other countries (Afghanistan, Algeria, Bahrain, 
Bangladesh, Egypt, Eritrea, Indonesia, Jordan, Kuwait, Lebanon, 
Morocco, North Korea, Oman, Qatar, Somalia, Tunisia, and the United 
Arab Emirates). The data exclude North Korea from the NSEERS countries 
tally because DHS did not provide information separately for North 
Korea and South Korea.

[F] Excludes countries in rows 1-4 of this table. Italicized rows below 
this category break out data for "Rest of world." 

[End of table]

[End of section]

Appendix VI: Four Prior Recommendations on Overstay Tracking, Data, or 
Estimates:

The following four prior recommendations to DHS concern overstay 
tracking, data, or estimates.

We recommended that to improve the collection of departure forms, the 
Commissioner of the Immigration and Naturalization Service should 
ensure that INS examine the quality control of the Nonimmigrant 
Information System database and determine why departure forms are not 
being recorded. This could involve, for example, examining a sample of 
the passenger manifest lists of flights with foreign destinations to 
determine the extent of airline compliance and, possibly, developing 
penalties to be levied on airlines for noncompliance. Discovery of the 
incidence of various causes of departure loss could allow a more 
precise estimation of their occurrence and the development of possible 
remedies. (U.S. General Accounting Office, Illegal Aliens: Despite Data 
Limitations, Current Methods Provide Better Population Estimates, GAO/
PEMD-93-25 (Washington, D.C.: Aug. 5, 1993).)

INS agreed in principle with our recommendation and fielded a pilot 
project to study why departure forms were not being collected. In 2002, 
INS discontinued the pilot because it was not yielding results INS had 
hoped for and because INS was in the process of designing an automated 
entry-exit system, which is now part of DHS's US-VISIT program. If 
successfully implemented, US-VISIT could help identify overstays. We 
are monitoring the design and implementation of the US-VISIT program.

We recommended that the Commissioner of INS have new overstay estimates 
prepared for air arrivals from all countries, using improved estimation 
procedures such as those discussed in the report, including, as 
appropriate, the potential improvements suggested by INS or by 
reviewers of the report. (U.S. General Accounting Office, Illegal 
Immigration: INS Overstay Estimation Methods Need Improvement, GAO/
PEMD-95-20 (Washington, D.C.: Sept. 26, 1995).)

INS initially concurred and produced revised estimates as part of its 
comments on our report. However, in our response to INS's comments, we 
described the new estimates as a "first step" and identified concerns 
about INS's methodological procedures that we said needed further 
study. Recently, DHS told us that it has not further studied making 
overstay estimates for air arrivals. Valid estimation of overstays is 
extremely difficult, given current tracking system weaknesses.

We recommended that to promote compliance with the change of address 
notification requirements through publicity and enforcement and to 
improve the reliability of its alien address data, the Attorney General 
should direct the INS Commissioner to identify and implement an 
effective means of publicizing the change of address notification 
requirement nationwide. INS should make sure, in its publicity effort, 
that aliens are given information on how to comply with this 
requirement, including information on where change of address forms and 
other information may be available. (U.S. General Accounting Office, 
Homeland Security: INS Cannot Locate Many Aliens Because It Lacks 
Reliable Address Information, GAO-03-188 (Washington, D.C.: Nov. 21, 
2002).)

DHS concurred with this recommendation and has identified it as a long-
term strategy that will require 2 years to fully implement. Since we 
made this recommendation less than 2 years ago, DHS has not had 
sufficient time to implement it fully.

We recommended that to provide better information on H-1B workers and 
their status changes, the Secretary of DHS take action to ensure that 
information on prior visa status and occupations for permanent 
residents and other employment-related visa holders is consistently 
entered into current tracking systems and that such information become 
integrated with entry and departure information when planned tracking 
systems are complete. (U.S. General Accounting Office, H-1B Foreign 
Workers: Better Tracking Needed to Help Determine H-1B Program's 
Effects on U.S. Workforce, GAO-03-883 (Washington, D.C.: Sept. 10, 
2003).)

DHS concurred with this recommendation. Sufficient time has not elapsed 
for DHS to implement this recommendation.

[End of section]

Appendix VII: Data from Operation Tarmac and Other Operations:

Table 6: Numbers of Illegal Immigrant Workers (and Overstays) Arrested 
in Selected Operation Tarmac Airports, by Nationality:

Airport: Atlanta Hartsfield (ATL); 
Mexican: 0 (0); 
Other Latin American[A]: 1 (0); 
NSEERS countries: 1 (0); 
Other countries[B]: 16 (14).

Airport: Austin (AUS); 
Mexican: 23 (1); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 0 (0).

Airport: Baltimore (BWI); 
Mexican: 0 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 3 (3).

Airport: Boston Logan (BOS); 
Mexican: 2 (0); 
Other Latin American[A]: 7 (1); 
NSEERS countries: 2 (2); 
Other countries[B]: 8 (3).

Airport: Burbank, California (BUR); 
Mexican: 5 (1); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 5 (4).

Airport: Chicago O'Hare (ORD) and Midway (MDW); 
Mexican: 23 (5); 
Other Latin American[A]: 7 (2); 
NSEERS countries: 1 (0); 
Other countries[B]: 7 (3).

Airport: Dallas (DFW); 
Mexican: 33 (7); 
Other Latin American[A]: 32 (17); 
NSEERS countries: 0 (0); 
Other countries[B]: 2 (2).

Airport: Denver (DIA); 
Mexican: 38 ( 4); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 1 (0); 
Other countries[B]: 2 (2).

Airport: Detroit (DTW); 
Mexican: 4 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 1 (1); 
Other countries[B]: 1 (1).

Airport: Houston Bush (IAH); 
Mexican: 96 (3); 
Other Latin American[A]: 7 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 0 (0).

Airport: Jacksonville (JAX); 
Mexican: 1 (0); 
Other Latin American[A]: 2 (2); 
NSEERS countries: 0 (0); 
Other countries[B]: 0 (0).

Airport: Los Angeles (LAX); 
Mexican: 18 (1); 
Other Latin American[A]: 1 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 4 (4).

Airport: Manchester, New Hampshire (MHT); 
Mexican: 1 (1); 
Other Latin American[A]: 2 (1); 
NSEERS countries: 0 (0); 
Other countries[B]: 1 (1).

Airport: Newark, New Jersey (EWR); 
Mexican: 0 (0); 
Other Latin American[A]: 12 (7); 
NSEERS countries: 0 (0); 
Other countries[B]: 1 (1).

Airport: New York JFK and LaGuardia (LGA); 
Mexican: 0 (0); 
Other Latin American[A]: 6 (0); 
NSEERS countries: 1 (1); 
Other countries[B]: 19 (10).

Airport: Omaha (OMA); 
Mexican: 8 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other countries[B]: 1 (0).

Airport: Orlando (MCO); 
Mexican: 0 (0); 
Other Latin American[A]: 11 (11); 
NSEERS countries: 0 (0); 
Other countries[B]: 2 (1).

Airport: Phoenix Sky Harbor (PHX); 
Mexican: 27 ( 6); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 ( 0); 
Other countries[B]: 1 (1).

Airport: Salt Lake City, Utah (SLC); 
Mexican: C; 
Other Latin American[A]: C; 
NSEERS countries: C; 
Other countries[B]: C.

Airport: San Francisco (SFO); 
Mexican: 4 (0); 
Other Latin American[A]: 2 (0); 
NSEERS countries: 1 (0); 
Other countries[B]: 10 (4).

Airport: Sarasota (SRQ); 
Mexican: 1 (0); 
Other Latin American[A]: 6 (1); 
NSEERS countries: 0 (0); 
Other countries[B]: 0 (0).

Airport: Tampa (TPA); 
Mexican: 1 (0); 
Other Latin American[A]: 8 (8); 
NSEERS countries: 0 (0); 
Other countries[B]: 2 (2).

Airport: Washington Dulles (IAD); 
Mexican: 9 (0); 
Other Latin American[A]: 32 (4); 
NSEERS countries: 1 (1); 
Other countries[B]: 5 (2).

Airport: Washington Reagan National (DCA); 
Mexican: 3 (1); 
Other Latin American[A]: 18 (7); 
NSEERS countries: 1 (0); 
Other countries[B]: 6 (5).

Total number; 
Mexican: 297 (30); 
Other Latin American[A]: 154 (61); 
NSEERS countries: 10 (5); 
Other countries[B]: 96 (63).

Percent; 
Mexican: 53.3% (18.9%); 
Other Latin American[A]: 27.7% (38.4%); 
NSEERS countries: 1.8% (3.1%); 
Other countries[B]: 17.2% (39.6%).

Source: U.S. Department of Homeland Security and GAO analysis.

Note: Data are for operations conducted from October 2001 through April 
2004. Numbers of overstays arrested are in parentheses. Because of 
missing nationality data, row totals may be lower than row totals in 
table 2 (which does not include nationality data).

[A] Excludes the Caribbean.

[B] Includes the Caribbean.

[C] Nationality data are not available.

[End of table]

Table 7: Illegal Immigrant Workers (and Overstays) Arrested in Critical 
Infrastructure and Special-Event Operations, by Nationality:

Operation: Big John (JFK carrier refitting shipyard); 
Mexican: 33 (1); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 0 (0).

Operation: Deny Access San Diego (shipyards); 
Mexican: 15 (1); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 1 (0).

Operation: Ensure West (Lawrence, Berkeley, and Livermore); 
Mexican: 1 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 2 (0).

Operation: Federal Protective Service (DC); 
Mexican: 0 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 2 (2).

Operation: Federal Protective Service (San Francisco); 
Mexican: 1 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0(0); 
Other[B]: 0 (0).

Operation: Fort Dix/McGuire (New Jersey); 
Mexican: 0 (0); 
Other Latin American[A]: 10 (5); 
NSEERS countries: 0 (0); 
Other[B]: 6 (4).

Operation: Game Day (San Diego Super Bowl); 
Mexican: 47 (6); 
Other Latin American[A]: 1 (1); 
NSEERS countries: 12 (0); 
Other[B]: 19 (1).

Operation: Glow Worm (nuclear power plants); 
Mexican: 1 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 0 (0).

Operation: Hub Cap LA (taxi drivers); 
Mexican: 4 (0); 
Other Latin American[A]: 4 (1); 
NSEERS countries: 9 (5); 
Other[B]: 16 (14).

Operation: Kurburdis (Air Force Academy); 
Mexican: 23 (2); 
Other Latin American[A]: 12 (0); 
NSEERS countries: 0 (0); 
Other[B]: 0 (0).

Operation: Pipe Line (Alaska); 
Mexican: 1 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 2 (0).

Operation: Security Breach II (Miami port); 
Mexican: 0 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 8 (1).

Operation: Sensitive national landmarks[C]; 
Mexican: 8(0); 
Other Latin American[A]: 14(6); 
NSEERS countries: 0(0); 
Other[B]: 2(2).

Operation: Sikorsky (Hartford, Connecticut); 
Mexican: 5 (0); 
Other Latin American[A]: 11 (7); 
NSEERS countries: 0 (0); 
Other[B]: 1 (0).

Operation: Warren AFB (Colorado); 
Mexican: 31 (0); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 0 (0).

Operation: Woodworker (Fort Leonard Wood); 
Mexican: 5 (2); 
Other Latin American[A]: 0 (0); 
NSEERS countries: 0 (0); 
Other[B]: 0 (0).

Total number: Critical infrastructure and special-event operations; 
Mexican: 175 (12); 
Other Latin American[A]: 52 (20); 
NSEERS countries: 21 (5); 
Other[B]: 59 (24).

Percent; 
Mexican: 57.0% (19.7%); 
Other Latin American[A]: 16.9% (32.8%); 
NSEERS countries: 6.8% (8.2%); 
Other[B]: 19.2% (39.3%).

Overall total number: Selected Tarmac airports and critical 
infrastructure and special-event locations; 
Mexican: 472 (42); 
Other Latin American[A]: 206 (81); 
NSEERS countries: 31 (10); 
Other[B]: 155 (87).

Percent; 
Mexican: 54.6% (19.1%); 
Other Latin American[A]: 23.8% (36.8%); 
NSEERS countries: 3.6% (4.6%); 
Other[B]: 17.9% (39.6%). 

Source: U.S. Department of Homeland Security and GAO analysis.

Note: Data are for operations conducted starting in 2002 and continuing 
through April 2004. Numbers of overstays arrested are in parentheses. 
Because of missing nationality data, row totals for this table may be 
lower than row totals in table 3 (which does not include nationality 
data).

[A] Excludes the Caribbean.

[B] Includes the Caribbean.

[C] Refers to multiple locations; landmark names are not specified for 
security reasons.

[End of table]

[End of section]

Appendix VIII: Key to References in Figure 1:

The references in this appendix are full bibliographic citations keyed 
to the GAO report numbers listed in figure 1.

Overseas: Tracking Terrorists and Visa Issuance:

Border Security: New Policies and Increased Interagency Coordination 
Needed to Improve Visa Process. GAO-03-1013T. Washington, D.C.: July 
15, 2003.

Border Security: New Policies and Procedures Are Needed to Fill Gaps in 
the Visa Revocation Process. GAO-03-798. Washington, D.C.: June 18, 
2003.

Information Technology: Terrorist Watch Lists Should Be Consolidated to 
Promote Better Integration and Sharing. GAO-03-322. Washington, D.C.: 
April 15, 2003.

Weaknesses in Screening Entrants into the United States. GAO-03-438T. 
Washington, D.C.: January 30, 2003.

Major Management Challenges and Program Risks: Department of State. 
GAO-03-107. Washington, D.C.: January 1, 2003.

Border Security: Implications of Eliminating the Visa Waiver Program. 
GAO-03-38. Washington, D.C.: November 22, 2002.

Border Security: Visa Process Should Be Strengthened as an 
Antiterrorism Tool. GAO-03-132NI. October 21, 2002.

National Preparedness: Integrating New and Existing Technology and 
Information Sharing into an Effective Homeland Security Strategy. 
GAO-02-811T. Washington, D.C.: June 7, 2002.

Embassy Security: Background Investigations of Foreign Employees. GAO/
NSIAD-89-76. January 5, 1989.

Border Security:

Security: Counterfeit Identification Raises Homeland Security 
Concerns. GAO-04-133T. October 1, 2003.

Homeland Security: Risks Facing Key Border and Transportation Security 
Program Need to Be Addressed. GAO-03-1083. September 19, 2003.

Land Border Ports of Entry: Vulnerabilities and Inefficiencies in the 
Inspections Process. GAO-03-1084R. August 18, 2003.

Border Security: New Policies and Increased Interagency Coordination 
Needed to Improve Visa Process. GAO-03-1013T. July 15, 2003.

Counterfeit Documents Used to Enter the United States from Certain 
Western Hemisphere Countries Not Detected. GAO-03-713T. May 13, 2003.

Border Security: Challenges in Implementing Border Technology. 
GAO-03-546T. March 12, 2003.

Technology Assessment: Using Biometrics for Border Security, 
GAO-03-174. November 15, 2002.

Internal Enforcement and Tracking:

H-1B Foreign Workers: Better Tracking Needed to Help Determine H-1B 
Programs Effects on U.S. Workforce. GAO-03-883. September 10, 2003.

Information Technology: Homeland Security Needs to Improve Entry Exit 
System Expenditure Planning. GAO-03-563. June 9, 2003.

Homeland Security: Justice Department's Project to Interview Aliens 
after September 11, 2001. GAO-03-459. April 11, 2003.

Homeland Security: Challenges to Implementation of the Immigration 
Interior Enforcement Strategy. GAO-03-660T. April 10, 2003.

Homeland Security: INS Cannot Locate Many Aliens Because It Lacks 
Reliable Address Information. GAO-03-188. November 21, 2002.

Immigration Benefits: Several Factors Impede Timeliness of Application 
Processing. GAO-01-488. May 4, 2001.

Illegal Immigration: INS Overstay Estimation Methods Need Improvement. 
GAO/PEMD-95-20. September 26, 1995.

Illegal Aliens: Despite Data Limitations, Current Methods Provide 
Better Population Estimates. GAO/PEMD-93-25. August 5, 1993.

Domestic Identity Fraud:

Social Security Administration: Actions Taken to Strengthen Procedures 
for Issuing Social Security Numbers to Noncitizens but Some Weaknesses 
Remain. GAO-04-12. October 15, 2003.

Social Security Administration: Disclosure Policy for Law Enforcement 
Allows Information Sharing, but SSA Needs to Ensure Consistent 
Application. GAO-03-919. September 30, 2003.

Social Security Numbers: Improved SSN Verification and Exchange of 
States' Driver Records Would Enhance Identity Verification. GAO-03-920. 
September 15, 2003.

Security: Counterfeit Identification and Identification Fraud Raise 
Security Concerns. GAO-03-1147T. September 9, 2003.

Supplemental Security Income: SSA Could Enhance Its Ability to Detect 
Residency Violations. GAO-03-724. July 29, 2003.

Social Security Numbers: Ensuring the Integrity of the SSN. 
GAO-03-941T. July 10, 2003.

Identity Fraud: Prevalence and Links to Alien Illegal Activities. 
GAO-02-830T. June 25, 2002.

Customs and INS: Information on Inspection, Infrastructure, Traffic 
Flow, and Security Matters at the Detroit Port of Entry. GAO-02-595R. 
April 22, 2002.

INS Forensic Document Laboratory: Several Factors Impeded Timeliness of 
Case Processing. GAO-02-410. March 13, 2002.

Identity Theft: Prevalence and Cost Appear to Be Growing. GAO-02-363. 
March 1, 2002.

Identity Theft: Available Data Indicate Growth in Prevalence and Cost. 
GAO-02-424T. February 14, 2002.

Illegal Aliens: Fraudulent Documents Undermining the Effectiveness of 
the Employment Verification System. GAO/T-GGD/HEHS-99-175. July 22, 
1999.

Illegal Aliens: Significant Obstacles to Reducing Unauthorized Alien 
Employment Exist. GAO/GGD-99-33. April 2, 1999.

Critical Infrastructure Protection:

Homeland Security: Information Sharing Responsibilities, Challenges, 
and Key Management Issues. GAO-03-1165T. September 17, 2003.

Transportation Security: Federal Action Needed to Help Address Security 
Challenges. GAO-03-843. June 30, 2003.

Transportation Security Research: Coordination Needed in Selecting and 
Implementing Infrastructure Vulnerability Assessments. GAO-03-502. May 
1, 2003.

Transportation Security: Post-September 11th Initiatives and Long-Term 
Challenges. GAO-03-616T. April 1, 2003.

Responses of Federal Agencies and Airports We Surveyed about Access 
Security Improvements. GAO-01-1069R. August 31, 2001.

Aviation Security:

Aviation Security: Challenges Exist in Stabilizing and Enhancing 
Passenger and Baggage Screening Operations. GAO-04-440T. February 12, 
2004.

Aviation Security: Computer-Assisted Passenger Prescreening System 
Faces Significant Implementation Challenges. GAO-04-385. February 13, 
2004.

Aviation Security: Transportation Security Administration Faces 
Immediate and Long-Term Challenges. GAO-02-971T. July 25, 2002.

Aviation Security: Information Concerning the Arming of Commercial 
Pilots. GAO-02-822R. June 28, 2002.

Aviation Security: Long-Standing Problems Impair Airport Screeners' 
Performance. GAO/RCED-00-75. June 28, 2000.

Aviation Security: Vulnerabilities Still Exist in the Aviation Security 
System. GAO/T-RCED/AIMD-00-142. April 6, 2000.

Aviation Security: FAA's Actions to Study Responsibilities and Funding 
for Airport Security and to Certify Screening Companies. GAO/
RCED-99-53. February 25, 1999.

Aviation Security: Implementation of Recommendations Is Under Way, but 
Completion Will Take Several Years. GAO/RCED-98-102. April 24, 1998.

Aviation Security: Posting Notices at Domestic Airports. GAO/
RCED-97-88R. March 25, 1997.

Aviation Safety and Security: Challenges to Implementing the 
Recommendations of the White House Commission on Aviation Safety and 
Security. GAO/T-RCED-97-90. March 5, 1997.

FOOTNOTES

[1] This report expands on our earlier testimony before the 
Subcommittee on Immigration, Border Security, and Claims, Committee on 
the Judiciary, House of Representatives: See U.S. General Accounting 
Office, Homeland Security: Overstay Tracking Is a Key Component of a 
Layered Defense, GAO-04-170T, Statement of Nancy R. Kingsbury, Managing 
Director, Applied Research and Methods (Washington, D.C.: Oct. 16, 
2003).

[2] The Visa Waiver Permanent program allows visitors from the 27 
countries listed in table 5, footnote d (app. V) to enter the United 
States without visas for up to 90 days for business or pleasure. (See 8 
U.S.C. §1187, 8 C.F.R. §217.2.) The majority of visitors from these 
countries do enter under the visa waiver program.

[3] Under certain circumstances, an application for extension or change 
of status can temporarily prevent a visitor's status from being 
categorized as illegal. See Janice Podolny, Chief, Inspections Law 
Division, Office of General Counsel, Immigration and Naturalization 
Service, U.S. Department of Justice, "Interpretation of 'Period of Stay 
Authorized by the Attorney General' in Determining 'Unlawful Presence' 
under INA §212(a)(9)(B)(ii)," memorandum, Washington, D.C., March 27, 
2003. See also Immigration and Naturalization Act (INA), §222(g).

[4] The Department of Homeland Security (DHS) states that the illegal 
or unauthorized resident population consists of (1) aliens who entered 
"the United States by crossing the border without inspection (EWIs 
[persons who entered without inspection])" and (2) "those who enter 
legally with a temporary visa and stay beyond the valid time limits…." 
Department of Homeland Security, Office of Immigration Statistics, 2002 
Yearbook of Immigration Statistics, (Washington, D.C.: U.S. Government 
Printing Office, Oct. 2003), pp. 213-14.

[5] This includes certain visits by Canadians, Mexicans, and citizens 
of visa waiver countries. 

[6] On March 1, 2003, the Immigration and Naturalization Service (INS) 
was transferred from the Department of Justice to DHS.

[7] In general, aliens who are present illegally in the United States 
are prohibited from obtaining green cards by adjusting, while here, to 
permanent resident alien (legal immigrant) status. There are 
exceptions; for example, this prohibition was waived for certain aliens 
who applied for such adjustment between 1994 and 2001 under INA 
§245(i). (See 8 U.S.C. §1255(i).)

[8] See (1) U.S. General Accounting Office, Border Security: New 
Policies and Increased Interagency Coordination Needed to Improve Visa 
Process, GAO-03-1013T (Washington, D.C.: July 15, 2003), p. 3, and (2) 
Information Technology: Terrorist Watch Lists Should Be Consolidated to 
Promote Better Integration and Sharing, GAO-03-322 (Washington, D.C.: 
Apr. 15, 2003), p. 28.

[9] See U.S. General Accounting Office, Homeland Security: First Phase 
of Visitor and Immigration Status Program Operating, but Improvements 
Needed, GAO-04-586 (Washington, D.C.: May 11, 2004). US-VISIT is 
discussed further in a later section of this report. Briefly, it is a 
new program for collecting, maintaining, and sharing information on 
foreign nationals. Its overall goals include (1) enhancing national 
security; (2) contributing to the integrity of the nation's immigration 
system; (3) facilitating legitimate border-crossing, trade, and travel; 
and (4) protecting privacy. 

[10] For example, some of the hijackers of September 11, 2001, were 
placed on U.S. watch lists after they entered the United States.

[11] Overstay tracking does not include surveillance, although when 
deemed appropriate, the information provided by overstay tracking may 
be used--by the Foreign Terrorist Tracking Task Force, for example--in 
combination with other kinds of information collection and analysis, 
including surveillance of suspected terrorists. (In contrast with 
overstay tracking, "terrorist tracking" can involve a broad range of 
tools aimed at locating terrorists and monitoring their activities 
abroad, as well as within the United States, if they were to slip 
across the borders.)

[12] This system is officially known as the Nonimmigrant Information 
System (NIIS).

[13] This applies to Canadians visiting or traveling through the United 
States. There are no perimeter restrictions for Canadians visiting the 
United States. DHS inspectors may, at their discretion, require any 
Canadian to fill out Form I-94.

[14] The Department of State considers the Mexican BCC, also termed a 
"USA B1/B2 VISA/BCC," to be (1) a visa authorizing its holder to be 
lawfully admitted to the United States temporarily for business or 
pleasure (for example, as a tourist), as well as (2) a BCC (that is, 
used with the 72-hour and perimeter limits). When the card is used as a 
visa, Form I-94 must be completed. It should also be noted that DHS 
inspectors may, at their discretion, require any Mexican using the card 
as a BCC to fill out Form I-94 as a condition of admission and that 
Form I-94 is required for visits that exceed 72 hours or include travel 
beyond the general 25-mile limit (in some cases in Arizona, travel up 
to 75 miles from the border is allowed). To qualify for a BCC, an 
applicant must demonstrate that he or she is a citizen and resident of 
Mexico. (See 8 C.F.R. §235.1 and 22 C.F.R. §41.33.)

[15] The other two-thirds were generally categorized as illegal border 
crossers, or EWIs (persons who entered without inspection). See U.S. 
Immigration and Naturalization Service, Office of Policy and Planning, 
Estimates of the Unauthorized Immigrant Population Residing in the 
United States: 1990 to 2000 (Washington, D.C.: Jan. 2003). We note that 
previous INS overstay estimates were higher than one-third. INS 
testified in 1999 that overstays constituted 40 to 50 percent of that 
population. See Michael D. Cronin, Acting Associate Commissioner, 
Programs, Immigration and Naturalization Service, Testimony Regarding 
Nonimmigrant Overstays before the Subcommittee on Immigration and 
Claims, House Judiciary Committee, U.S. Congress, Washington, D.C., 
March 18, 1999.

[16] By definition, short-term overstays are not part of the resident 
population that DHS estimated.

[17] Appendixes III and IV describe how DHS calculated its estimates of 
7 million illegal immigrants and 2.3 million overstays. See also U.S. 
General Accounting Office, Illegal Immigration: INS Overstay Estimation 
Methods Need Improvement, GAO/PEMD-95-20 (Washington, D.C.: Sept. 26, 
1995).

[18] The sample was drawn from nearly 150,000 adults who obtained their 
green cards in July and August 1996. See Douglas S. Massey and Nolan 
Malone, "Pathways to Legal Immigration," Population Research and Policy 
Review 21 (2002): 473-504.

[19] As we noted earlier, aliens present illegally in the United States 
are, with some exceptions, prohibited from obtaining green cards by 
adjusting to permanent resident alien status.

[20] While workers at the critical infrastructure locations tended to 
be from Mexico or other Latin American countries and less likely to be 
identified as overstays, the reverse pattern applied for retail chain 
employees.

[21] Earlier reports from INS and DOJ's Inspector General also 
indicated that overstays constituted substantial percentages of groups 
of illegal residents who legalized their status. See Immigration and 
Naturalization Service, Immigration Reform and Control Act: Report of 
the Legalized Alien Population (Washington, D.C.: 1992), and U.S. 
Department of Justice, Office of the Inspector General, Immigration and 
Naturalization Service Monitoring of Nonimmigrant Overstays, report 
I-97-08 (Washington, D.C.: 1997).

[22] As we explain in the background section of this report, the 
majority of Mexican and Canadian visits do not require Form I-94. DHS 
procedures for estimating the 7 million illegal immigrants would 
logically include long-term overstays in this group. However, DHS 
procedures for estimating the 2.3 million overstay settlers would, 
erroneously, not include them. Instead, DHS procedures erroneously 
categorize this group together with EWIs and other nonoverstay illegal 
immigrants (4.7 million).

[23] As we noted previously, the majority of Mexican and Canadian 
visits do not require Form I-94. The Department of State issued 6.4 
million BCCs to Mexican nationals during fiscal years 1999-2003.

[24] Specifically, DHS used Form I-94 data from the early 1990s and 
projected them forward to obtain the one-third overstay proportion. 
(See app. IV.)

[25] Appendixes III and IV give further information on how the DHS 
estimates were calculated.

[26] On the basis of limited DHS data for several airport sweeps, 
arrested Mexican workers who were identified and recorded as BCCs were 
categorized as overstays, in almost all cases. We believe this issue 
needs more study before drawing conclusions about the prevalence of 
such violators. For example, DHS staff told us that a Mexican with a 
BCC who is working in the United States may protect the BCC by using a 
different name and even mailing the BCC back to an address in Mexico.

[27] The main component of DHS's estimate of 7 million illegal 
residents is based on subtracting foreign-born persons here legally 
(who are reflected in statistical immigration records) from census 
counts of total foreign-born; subtraction is carried out separately for 
annual cohorts who arrived in the United States after 1990.

[28] U.S. General Accounting Office, H-1B Foreign Workers: Better 
Tracking Needed to Help Determine H-1B Program's Effects on U.S. 
Workforce, GAO-03-883 (Washington, D.C.: Sept. 10, 2003), p. 5. See 
also U.S. General Accounting Office, Immigration Benefits: Several 
Factors Impede Timeliness of Application Processing, GAO-01-488 
(Washington, D.C.: May 4, 2001).

[29] U.S. General Accounting Office, Homeland Security: INS Cannot 
Locate Many Aliens Because It Lacks Reliable Address Information, 
GAO-03-188 (Washington, D.C.: Nov. 21, 2002).

[30] GAO/PEMD-95-20, p. 2. See also U.S. General Accounting Office, 
Illegal Aliens: Despite Data Limitations, Current Methods Provide 
Better Population Estimates, GAO/PEMD-93-25 (Washington, D.C.: Aug. 5, 
1993).

[31] Our investigators have tested DHS inspectors by using counterfeit 
driver's licenses and fictitious names to enter the United States from 
Barbados, Canada, Jamaica, and Mexico; DHS did not question the 
authenticity of the counterfeit documents (see U.S. General Accounting 
Office, Security: Counterfeit Identification and Identification Fraud 
Raise Security Concerns, GAO-03-1147T (Washington, D.C.: Sept. 9, 
2003).)

[32] See U.S. General Accounting Office, Homeland Security: Challenges 
to Implementing the Immigration Interior Enforcement Strategy, 
GAO-03-660T (Washington, D.C.: Apr. 10, 2003), p. 1.

[33] NSEERS domestic registration required selected groups of aliens 
from a number of countries to register with immigration authorities 
between November 2002 and April 2003. About 13,900 aliens identified 
through NSEERS were issued a "Notice to Appear" to show cause why they 
should not be deported. As of February 2004, more than 350 of these had 
been removed from the United States, with the majority of the cases 
still unresolved.

[34] They calculated this by counting arrests for all legal visitors 
and overstays, including the targeted groups, and dividing by DHS's 
estimate of the resident overstay population.

[35] An earlier pilot program intended to address some of these 
weaknesses was discontinued in 2002. See U.S. Department of Justice, 
Office of the Inspector General, Immigration and Naturalization Service 
Monitoring of Nonimmigrant Overstays, report I-97-08 (Washington, D.C.: 
Sept. 1997), The Immigration and Naturalization Service's Automated I-
94 System, report 01-18 (Washington, D.C.: Aug. 2001), and Follow-Up 
Report on INS Efforts to Improve the Control of Nonimmigrant Overstays, 
report I-2002-006 (Washington, D.C.: Apr. 2002).

[36] NSEERS POE has focused on eight countries: Iran, Iraq, Libya, 
Pakistan, Saudi Arabia, Sudan, Syria, and Yemen. (Seventeen additional 
countries were included in the NSEERS domestic registration component 
of this program.)

[37] U.S. General Accounting Office, Homeland Security: Risks Facing 
Key Border and Transportation Security Program Need to Be Addressed, 
GAO-03-1083 (Washington, D.C: Sept. 19, 2003), p. 27. See also Homeland 
Security: Risks Facing Key Border and Transportation Security Program 
Need to Be Addressed, GAO-04-569T, (Washington, D.C.: Mar. 18, 2004), 
p. 4.

[38] The broad, overall goals of US-VISIT are described in an earlier 
footnote. See also GAO-04-586.

[39] GAO-03-1083.

[40] GAO-04-586.

[41] GAO-03-188 and Land Border Ports of Entry: Vulnerabilities and 
Inefficiencies in the Inspections Process, GAO-03-1084R (Washington, 
D.C.: Aug. 18, 2003).

[42] Those with a "history of overstaying" had been overstays at an 
earlier point in time but subsequently adjusted to a legal status.

[43] Overall, three current or prior overstays were associated with 
eight different September 11 hijackers, typically facilitating identify 
fraud.

[44] See U.S. General Accounting Office, Homeland Security: Justice 
Department's Project to Interview Aliens after September 11, 2001, 
GAO-03-459 (Washington, D.C.: Apr. 11, 2003). In that report, we also 
reviewed other problems with the post-September 11 interviewing 
initiative.

[45] GAO-03-188.

[46] After September 11, DHS shifted its interior enforcement focus to 
jobs with access to sensitive areas, such as critical infrastructures.

[47] Operation Tarmac is conducted through joint investigations with 
the U.S. Attorney's Office, DOJ, and the Federal Bureau of 
Investigation (FBI), DHS, the Department of Transportation (DOT), and 
the Social Security Administration (SSA), as well as airport security 
and local sheriff and police departments.

[48] All U.S. employers are responsible for the completion and 
retention of Form I-9 for each individual hired to work in the United 
States after November 6, 1986. This includes citizens and noncitizens. 
On Form I-9, the employer must verify the employment eligibility and 
identity documents employees present and record the document 
information. Acceptable documents are listed on the back of the form. 

[49] Note that the parameters of each airport sweep were decided in the 
field. Some, like Houston, reviewed all levels of badges. Others, like 
Chicago, where the U.S. Attorneys have a heavy caseload, prosecuted 
only cases in which copies of the fraudulent documents were presented, 
copied by the employer, retained, and available as evidence. 
Consequently, comparisons between airport sweeps may not be 
appropriate.

[50] Efforts to combat domestic identity fraud are part of the nation's 
layered defense, and we have reported that "identity theft is often an 
essential component . . . [of] . . . international terrorism." (See 
U.S. General Accounting Office, Identity Fraud: Prevalence and Links to 
Alien Illegal Activities, GAO-02-830T (Washington, D.C.: June 25, 
2002), p. 9.) 

[51] Such employees must have a security badge to work in (or escort 
others into) a secure area. 

[52] DHS officials told us that obtaining a security badge by 
fraudulent means is a felony.

[53] Airport badging authorities vary. They can be city officials, 
airport or port authority officials, and even state police. For more on 
the Transportation Security Administration's (TSA) steps to reduce the 
security risks posed by workers, see U.S. General Accounting Office, 
Aviation Security: Further Steps Needed to Strengthen the Security of 
Airport Perimeters and Access Controls, GAO-04-500 (Washington, D.C.: 
Apr. 30, 2004).

[54] Airport badging authorities cannot use DHS's Basic Pilot program, 
which allows employers to simultaneously check Social Security and 
immigration data (with the exception of checking their own new hires--
in states where the program is active). Last year, legislation aimed in 
part at addressing these issues was introduced in the U.S. House of 
Representatives (H.R. 2359) but did not pass. Although airport badging 
authorities that qualify as government agencies could use DHS's SAVE 
(Systematic Alien Verification) program (intended to check the 
immigration status of persons applying for government benefits), DHS 
officials advised us that SAVE should not be described as a way for 
critical infrastructure employers or security authorities to 
comprehensively screen all employees for employment eligibility. 
Another possible alternative, DHS's Law Enforcement Support Center, can 
verify immigration status only for aliens suspected or convicted of 
criminal activity; it does not perform employment eligibility status 
verification. 

[55] Stricter background checks or physical screening have been 
proposed in H.R. 4312, the Safe Passengers and Lading in Aviation for 
the National Enhancement of Security Act, introduced May 6, 2004.

[56] U.S. Immigration and Naturalization Service, Office of Policy and 
Planning, "Estimates of the Unauthorized Immigrant Population Residing 
in the United States: 1990 to 2000," Washington, D.C., January 2003. 
These DHS estimates were made using data and estimates through December 
31, 1999, but DHS characterizes them for January 2000.

[57] Short-term illegal aliens in the United States the year before or 
following but not during the time of the census would not be included. 
Other short-term alien residents might not identify the United States 
as their primary place of residence and so would be excluded from the 
census. 

[58] The long form of the census asks whether each member of the 
household is a U.S. citizen and where each was born. Each person born 
outside the United States is asked when he or she first came to the 
United States to live. DHS adjusted the census data, gathered in spring 
2000, to reflect residents here as of December 31, 1999. Administrative 
data used in the residual estimates were organized by calendar year. 

[59] Those counted as legal had "gained temporary protection against 
removal by applying for an immigration benefit" (U.S. Immigration and 
Naturalization Service, "Estimates of the Unauthorized Immigrant 
Population Residing in the United States: 1990 to 2000," p. 3). 
"Asylee" refers to an alien granted asylum, "parolee" an alien 
otherwise inadmissible but allowed to enter temporarily for urgent 
humanitarian reasons or significant public benefit. Temporary protected 
status derives from the U.S. Attorney General's designating foreign 
nationals eligible for temporary refuge. 

[60] U.S. Immigration and Naturalization Service, "Estimates of the 
Unauthorized Immigrant Population Residing in the United States: 1990 
to 2000," pp. 3 and 18.

[61] The INS paper provides neither a detailed explanation of how the 
3.5 million estimate was derived nor a reference to an earlier 
publication. 

[62] According to DHS, the following groups were subtracted from the 
earlier 3.5 million estimate (each defined according to the relevant 
time period): (1) illegal residents removed by INS, based on removal 
records; (2) estimated age-standardized deaths, based on the age 
distribution of the population that was legalized in the late-1980s 
amnesty and on survival rates for Hispanics residing in the United 
States; (3) a potentially uncertain estimate of the number of illegal 
residents who emigrated from the United States; and (4) estimates of 
the numbers who adjusted to lawful status while in the United States or 
after briefly exiting the United States, based on INS records regarding 
numbers of "green cards" issued, time in the United States before 
receiving green cards, and patterns observed before and after changes 
in laws on whether illegal residents can apply for adjustment to legal 
status without leaving the United States. 

[63] Estimates by state were also made. 

[64] See Jeffrey S. Passel, "Undocumented Immigration to the United 
States: Numbers, Trends, and Characteristics," p. 29, in David W. 
Haines and Karen E. Rosenblum, eds., Illegal Immigration in America: A 
Reference Handbook (Westport, Conn.: Greenwood Press, 1999). 

[65] We note that a Census Bureau working paper estimated the 
"residual" population in 1990, consisting of illegal and "quasilegal" 
residents, at 3.8 million--or, for illustrative purposes, assuming a 15 
percent undercount rate in the 1990 census, 4.4 million. See Joseph 
Costanzo and others, Evaluating Components of International Migration: 
The Residual Foreign Born, Population Division Working Paper 61 
(Washington, D.C.: U.S. Bureau of the Census, June 2002). Census 
working papers are the results of research by Census Bureau staff and 
undergo a more limited review than official Census Bureau publications. 

[66] U.S. Immigration and Naturalization Service, "Estimates of the 
Unauthorized Immigrant Population Residing in the United States: 1990 
to 2000." (DHS's estimate of 7 million is discussed in app. III.) 

[67] BCC refers to the border crossing card, described in the report. 

[68] GAO/PEMD-95-20, pp. 21-26. 

[69] An illustration of potential problems in INS's procedure is the 
different airlines' different rates of "system error" that INS 
procedures did not account for. The simple subtraction procedure was 
also erroneous--that is, INS's formula was incorrect (see GAO/PEMD-95-
20, app. I). 

[70] Robert Warren, "Estimates of the Undocumented Immigrant Population 
Residing in the United States, by Country of Origin and State of 
Residence: October 1992," undated revision of paper presented at 
California Immigration 1994, conference sponsored jointly by the Center 
for California Studies, California Research Bureau of the California 
State Library, and California Policy Seminar of the University of 
California, Sacramento, California, April 29, 1994. 

[71] U.S. Immigration and Naturalization Service, "Estimates of the 
Unauthorized Immigrant Population Residing in the United States: 1990 
to 2000," p. 6. 

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