geographic change notes

• Incorporating geographic changes for the post-2000 estimates series
• Summary of detailed changes found in these notes
• Future geographic changes
• Census 2000 corrections
• Census 1990 corrections
• Boundary files for estimates geography
• For more information

Source: U.S. Census Bureau
Release Date: October 1997
Revised: May 2006

The Census Bureau's population estimates are produced using annually updated decennial census base population counts. These updated counts are referred to as the "population estimates base" to distinguish them from previously published census population totals. The population estimates base reflects corrections, boundary changes, and other geographic updates since the last census. The geographic change notes describe the most significant of these changes and are intended to assist data users working with population estimates time series data.

Incorporating Geographic Changes for the Post-2000 Estimates Series

The post-2000 population estimates reflect legal boundary changes reported nationwide via the annual Boundary and Annexation Survey (BAS). In that survey, governmental units are asked to report the boundaries legally in effect as of January 1 of the current calendar year. Geographic changes collected via the BAS are incorporated annually into the estimates base, using an automated processing system termed the Geographic Update System to Support Intercensal Estimates (GUSSIE). Generally, all BAS changes submitted to the Census Bureau by April 1 of the calendar year will be reflected in the population estimates for that year.

In general, increases or decreases in land area are accompanied by corresponding changes in the base population of each governmental unit. When governmental units are merged, their respective base populations are combined. Base populations are calculated for new governmental units, and base populations of incorporated places or townships that dissolve become part of the unincorporated balances of the counties in which these governmental units are located. In other instances, base population increases or decreases in areas with few or insignificant boundary changes may reflect improvements in the geographic assignment capabilities of the Census Bureau’s TIGER® System and associated Master Address File.

     

Summary of Detailed Changes Found in These Notes

The notes are organized by state and currently include the following types of changes:

• Annexations and de-annexations of incorporated places only across boundaries of counties and county subdivisions.

• Formation of new governmental units.

• Disincorporations, dissolutions, and disorganizations of governmental units.

• Mergers and/or consolidations of governmental units.

• Governmental units not reported in the 2000 census that were legally in existence as of January 1, 2000 (the date used to determine reporting eligibility in that census).

• Governmental unit name changes.

• Geographic code changes (Census and FIPS [Federal Information Processing Standard]), listing the new and previous codes for a governmental unit.

• Legal/Statistical Area Description (LSAD) changes, listing the description of each governmental unit, such as a "village" becoming a "city."

• Dependency status changes, describing the relationship between an incorporated place and a functioning minor civil division or county. Places are either independent or dependent. Status changes require geographic code changes to ensure that the affected governmental units are structured into the appropriate hierarchical relationships.

• Functional status changes, specifying whether a governmental entity was activated or deactivated (some governmental units may remain legally in existence, but inactive, in which case estimates are not produced for the entity).

The following statistical areas are included in population estimates products:

• Alaska census areas are treated as borough (county) equivalents.

• Honolulu, HI Census Designated Place is treated as an incorporated place.

• Unorganized territories located in counties with functioning minor civil divisions (MCDs) are treated as MCD equivalents.

     

Future Geographic Changes

The Census Bureau is enacting post-Census 2000 programs, many in conjunction with local governments, to further improve the geographic information in the TIGER® System with direct benefits for the Population Estimates Program and the American Community Survey. This information will include census corrections and geographic boundary updates that occurred after Census 2000. The July 1, 2005 county and subcounty population estimates reflect boundary updating current to January 1, 2005 and Count Question Resolution corrections processed through September 30, 2003.

     

Census 2000 Corrections

Corrections to population counts resulting from the Census 2000 Count Question Resolution Program are not included in the notes, but are available for review and downloading on the Census Bureau’s Web site, at: http://www.census.gov/prod/cen2000/notes/errata.pdf.

1990 Census Corrections

Historical documentation about corrections resulting from the Census Bureau’s 1990 Count Question Resolution program is not on the Web site, but is available in a Census Bureau report, Corrected 1990 Census Population, Housing Units, and Group Quarters Counts for Governmental Units (CPH-L-157).

     

Boundary Files for Estimates Geography

Estimates geography boundary files for use in a geographic information system (GIS) or other mapping software are available for download. See http://www.census.gov/geo/www/cob/.

     

For more information on census geography refer to:

     

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