illicit drug use 2001 NHSDA State Estimates,

2.1. Any Illicit Drug

Past month estimates of use of any illicit drug ranged from a low of 4.1 percent in North Dakota to a high of 10.7 percent in Massachusetts for all persons age 12 or older based on the combined 2000–2001 NHSDA data (Figure 2.1; Table B.1). Overall, the estimates were quite similar for the combined 1999–2000 data and combined 2000–2001 data with a correlation of 0.92 for all persons age 12 or older. The correlations for the other age groups ranged from 0.90 to 0.94.

The estimates for 2000–2001 have precision that is similar to that for 1999–2000. For example, given the estimate above for North Dakota (4.1 percent), the probability is 95 percent that the true value for North Dakota lies somewhere between 3.3 and 5.0 percent. This interval is approximately one quarter smaller than the corresponding interval for North Dakota based on a single year's data.¹

The States with the highest rates of any illicit drug use for all persons age 12 or older were mostly in the East (five States) for 2000–2001 as opposed to the West (six States) for 1999–2000. The top States in the East were entirely in New England (Massachusetts, Vermont, Maine, Rhode Island, and New Hampshire). Massachusetts, Rhode Island, and Vermont also were in the top fifth in 1999–2000. The four Western States in the top fifth in 2000–2001 also were in the top fifth in 1999–2000 (Colorado, Alaska, Oregon, and California). Most of the States that displayed the lowest rates in the Nation were either from the Midwest (five States) or the South (three States). Utah and Idaho completed the lowest fifth.

Reflecting the significant increase in the national estimates over this period from 6.3 to 6.7 percent for all persons age 12 or older,² 38 out of 51 States (including the District of Columbia) had higher estimates in 2000–2001 than in 1999–2000; however, only increases for 6 States were statistically significant at the 0.10 level or better.³ Those States were Arkansas (from 5.4 to 6.7 percent), Illinois (from 6.3 to 7.2 percent), Maine (from 6.9 to 8.4 percent), New Hampshire (from 6.6 to 8.0 percent), New York (from 5.8 to 6.8 percent), and Vermont (from 8.5 to 10.5 percent). Most of these increases were driven by statistically significant increases in the 18 to 25 age group: Arkansas (from 13.8 to 18.3 percent), Illinois (from 16.4 to 18.9 percent), New Hampshire (from 19.8 to 25.5 percent), New York (from 17.1 to 19.3 percent), and Vermont (from 27.0 to 31.8 percent). Two other States showed significant increases among youths: Michigan (from 10.6 to 12.1 percent) and Pennsylvania (from 8.3 to 9.7 percent) (Table A.1).

Because only a small number of States had statistically significant changes at the 0.05 level or lower, here and throughout the text the discussion has been extended to include States that were statistically significantly different at the p = 0.10 level or lower. Another criterion that sometimes has been used in the analysis is a change in the rank by two or more quintiles (e.g., a change in a State's rank from the top fifth [quintile 5] in 1999–2000 to the middle fifth [quintile 3] in 2000–2001). For example, Indiana, Kansas, Michigan, New Jersey, and New York showed changes of two quintiles between the previous State report and this one in one or more age groups (12 to 17, 18 to 25, 26 or older, or 12 or older). Only Indiana and New Jersey displayed decreases of two or more rank categories. Indiana's ranking decreased by two quintiles for the 12 or older age group, the 26 or older age group, and the 18 to 25 age group. New Jersey showed a two-quintile decrease in its ranking for the 12 to 17 age group.

2.2. Marijuana

Because marijuana is the predominant substance used by those using an illicit drug, many of the States that showed high prevalence rates for any illicit drug also had high prevalence rates for past month use of marijuana. For example, eight of the States in the top fifth for use of an illicit drug for persons age 12 or older also were ranked in the top fifth for past month use of marijuana: Massachusetts, Vermont, Colorado, Alaska, Oregon, Maine, Rhode Island, and New Hampshire (Figures 2.1 and 2.5; Table s B.1 and B.2). In the 12 to 17 age group, eight States were in the top fifth for both use of any illicit drug and use of marijuana: Vermont, Massachusetts, New Hampshire, Maine, New Mexico, Colorado, Connecticut, and Rhode Island (Figures 2.2 and 2.6; Table s B.1 and B.2). Eight States were common to the top fifth for current marijuana use among persons age 12 or older and youths age 12 to 17: Vermont, Massachusetts, Colorado, Maine, Alaska, New Hampshire, Rhode Island, and Connecticut. In the rankings of State estimates, marijuana exhibited high correlations (0.91 or higher) of 1999–2000 rates with 2000–2001 rates for all age groups.

Eight States had statistically significant increases (p < 0.1) in past month marijuana use between 1999–2000 and 2000–2001 for the 12 or older age group. Five of them were the same States that had significant increases for past month use of any illicit drug: Arkansas, Illinois, Maine, New York, and Vermont. The other States were Iowa, Kansas, and Mississippi. New York showed the only significant increase for the 26 or older age group (from 2.4 to 3.1 percent). Arkansas (from 10.0 to 14.5 percent) and Illinois (from 14.3 to 16.8 percent) displayed the only significant changes for the 18 to 25 age group. Kentucky, Michigan, and Delaware were the only States having significant changes among youths age 12 to 17. Kentucky's past month rate of use of marijuana increased from 6.8 to 9.0 percent, and Michigan's rate increased from 7.9 to 9.4 percent; however, Delaware showed a decrease from 11.9 to 9.6 percent (Table s A.1 and A.2).

2.3. Perceptions of Risk of Marijuana Use

An individual's perceptions of the risks of substance use have been shown to be related to whether he or she actually uses the substance (e.g., Bachman, Johnston, & O'Malley, 1998; Lane, Gerstein, Huang, & Wright, 2001). In 1999–2000 and again in 2000–2001, the State with the lowest rate of perceived great risk of using marijuana occasionally (once a month) among persons age 12 or older was Vermont (Figure 2.9; Table A.3). Only about 28 percent of all persons age 12 or older in Vermont thought that occasional use was a great risk. Vermont had the highest rate of past month use of marijuana in the 12 to 17 age group (13.2 percent), the 18 to 25 age group (28.6 percent), and for all persons age 12 or older (9.1 percent). By contrast, Mississippi reported the highest perceived risk of marijuana, about 54 percent of the 12 or older age group, but ranked in the lowest fifth in that age group for past month marijuana use (3.8 percent). Of the 10 States reporting the lowest perceived risk of marijuana use, 9 were in the top fifth for past month use of marijuana (Figures 2.5 and 2.9; Table s B.2 and B.3).

For the 12 or older age group, five States showed a significant decrease in perceived risk of using marijuana occasionally: Connecticut, District of Columbia, Louisiana, New York, and Ohio. The same States also showed decreases in perceived risk in at least one of the three component age groups. In addition, Hawaii had a decrease in the 12 to 17 age group (from 37.1 to 31.2 percent), and in the 18 to 25 age group, four States showed decreases during the period: District of Columbia (from 27.3 to 23.1 percent), Maine (from 21.1 to 16.6 percent), North Dakota (from 29.6 to 25.1 percent), and Vermont (from 18.6 to 14.5 percent). Alaska was the only State that showed a statistically significant increase in perceived risk in any of the age groups: from 35.0 to 39.7 percent in the 26 or older age group and from 32.4 to 35.8 percent in the 12 or older age group (Table A.3).

2.4. Incidence of Marijuana

Related to the prevalence of marijuana use is the number of persons in a period of time who used it for the first time ever. When the number of first-time users of a substance increases for a number of consecutive years, the prevalence rates for the substance tend to increase also.

Only two States showed significant changes between the 1999–2000 and 2000–2001 estimates. The average annual incidence of marijuana (averaged over the most recent 2 years and expressed as a percentage or rate per 100 person years of exposure) for all persons age 12 or older increased for Illinois, from approximately 1.6 to 1.8 percent (p = 0.07), and for Vermont, from 2.3 to 2.7 percent (p = 0.07). The average annual incidence of marijuana was highest in the 12 to 17 age group (Figure 2.14; Table s A.4 and B.4). In the 12 to 17 age group, Vermont had the highest rate in the Nation, 9.4 percent. Of the top 10 States, 4 were in the West: New Mexico, Nevada, Hawaii, and Colorado. By comparison, the highest rate for all persons age 12 or older was significantly lower, only 2.7 percent in Vermont (Figure 2.13; Table B.4). For youths age 12 to 17, Utah (4.7 percent) had the lowest incidence rate for the Nation. Six of the ten States in the lowest fifth for marijuana incidence for youths were in the South.

Rates of incidence of marijuana use were highly correlated at the State level with prevalence rates for current (i.e., past month) use of marijuana and any illicit drug use for youths age 12 to 17. Rates were somewhat less correlated for the other age groups. Five of the States in the top fifth for youth incidence of marijuana also were in the top fifth for past month use (Figures 2.6 and 2.14; Table s B.2 and B.4).

In the 12 to 17 age group, first-time users of marijuana comprised a large percentage of those reporting current use of marijuana. Even though the incidence rate (based on an annual average over the past 2 years) and the prevalence rate of current marijuana use (based on the past month) are not strictly comparable, one can be expressed as a ratio relative to the other. The ratio of the incidence rate relative to the past month prevalence rate for marijuana in the 12 to 17 age group was the highest of all age groups. At the national level, this ratio was approximately 30 percent (1.5 percent/4.8 percent).

2.5. Any Illicit Drug Other Than Marijuana

In the 12 or older age group and in the 18 to 25 age group, rates of past month use of these drugs were highest in Vermont (3.6 and 10.5 percent, respectively) (Figures 2.16 and 2.18; Table B.5). The top fifth for persons age 12 or older was comprised of four States in the West (California, Arizona, Colorado, and Nevada), three New England States (Vermont, Massachusetts, and New Hampshire), and three States in the South (Louisiana, District of Columbia, and Arkansas). Seven of these States fell into the top fifth for this age group in 1999–2000 (Table A.5). States from the Midwest dominated the lower fifth for the 12 or older age group (Nebraska, Iowa, South Dakota, North Dakota, Missouri, Ohio, and Indiana). The three other States in the lowest fifth were Idaho, Florida, and New Jersey.

The correlation (0.82) in the 12 or older age group between the State estimates for 1999–2000 and for 2000–2001 for any illicit drug other than marijuana was lower than the correlations for the other substances. Part of the reason may be the relatively lower prevalence rates for this category. The only statistically significant changes in State prevalence rates between 1999–2000 and 2000–2001 occurred in the 18 to 25 age group. Eight States showed positive increases in that period: Arizona (from 5.8 to 7.9 percent), Arkansas (from 6.0 to 8.1 percent), California (from 5.9 to 7.1 percent), Illinois (from 4.8 to 6.2 percent), New York (from 5.2 to 6.5 percent), Pennsylvania (from 5.9 to 7.2 percent), Texas (from 5.6 to 7.0 percent), and Virginia (from 4.9 to 7.1 percent) (Table A.5). A large number of States moved two or more quintiles in ranking, although most of those changes were not statistically significant. Arizona increased its rank in the 18 to 25 age group from the second to the fifth quintile (change between 1999–2000 and 2000–2001 was significant and indicated an increase in drug use). Arkansas increased its rank in the 12 or older age group from the second to the fifth quintile (not significant). West Virginia decreased its rank in the 18 to 25 age group from the fifth to the second (not significant). Arizona, Louisiana, and Vermont were the only States that were in the top fifth for all three age groups (12 to 17, 18 to 25, and 26 or older). Inhalants were the primary substance used by the 12 to 17 age group.

2.6. Cocaine

The national prevalence rate for the use of cocaine in the past year among all persons age 12 or older increased from 1.5 percent in 2000 to 1.9 percent in 2001 (OAS, 2002d). Because cocaine is one of the substances included in the "any illicit drug other than marijuana" category, it is useful to compare the rankings of States with respect to these two substance measures. As was true for 1999–2000, in 2000–2001 seven of the States with the 10 highest rates of past month use of an illicit drug other than marijuana (age 12 or older) also had past year rates of cocaine use (age 12 or older) that were in the top fifth. New Mexico and Colorado had the highest rate of past year use of cocaine (2.8 percent) among persons age 12 or older (Figure 2.20; Table B.6). Six out of ten of the States with the highest rates of cocaine use among youths age 12 to 17 were in the West. Four States (New Mexico, Arizona, Nevada, and Colorado) were in the top fifth for all three age groups (12 to 17, 18 to 25, and 26 or older) (Figures 2.21 to 2.23; Table B.6). The District of Columbia had the highest rate of past year cocaine use among persons age 26 or older.

In the 12 or older age group, the correlation of State estimates of 1999–2000 with 2000–2001 for past year use of cocaine was 0.84, and the correlation in the 26 or older age group was somewhat lower, 0.75. A major contributor to the slightly low correlations from year to year is the higher relative variation resulting from estimating a low prevalence rate. For the 12 or older age group, eight States with the highest prevalence rates in 2000–2001 also ranked in the highest fifth in 1999–2000. Across all age groups and for the composite 12 or older age group, only Hawaii showed a significant change during that period. Hawaii's past year use of cocaine among persons age 26 or older dropped from 1.5 percent in 1999–2000 to 0.8 percent in 2000–2001, accompanying a decrease of rank from the highest fifth to the lowest fifth. Cocaine use in New Hampshire increased from 1.4 to 1.8 percent among persons age 12 or older, but the increase was not statistically significant. However, New Hampshire may bear watching in the future because its overall rank increased by three quintiles (Table A.6).

Figure 2.1 Percentages Reporting Past Month Use of Any Illicit Drug among Persons Aged 12 or Older, by State: 2000 and 2001

Figure 2.1 D