1998 Annual Report

on Marijuana Use 

Among Arrestees

on Marijuana Use

Among Arrestees 

A Program of the National Institute of Justice

Research Report
U.S. Department of Justice

Office of Justice Programs

810 Seventh Street N.W.

Washington, DC 20531

Janet Reno

Attorney General

Raymond C. Fisher

Associate Attorney General

Laurie Robinson

Assistant Attorney General

Noel Brennan

Deputy Assistant Attorney General

Jeremy Travis

Director, National Institute of Justice

Office of Justice Programs 

World Wide Web Site

http://www.ojp.usdoj.gov

Justice Information Center

World Wide Web Site

http://www.ncjrs.org

National Institute of Justice

World Wide Web Site

http://www.ojp.usdoj.gov/nij

ADAM Program

World Wide Web Site

http://www.adam-nij.net

..
1998 Annual Report

on Marijuana Use

Among Arrestees 

A Program of the National Institute of Justice

Research Report
U.S. Department of Justice

Office of Justice Programs

National Institute of Justice

Jeremy Travis

Director

K. Jack Riley, Ph.D.

ADAM Director

NCJ 175658

The National Institute of Justice is a component of 

the Office of Justice Programs, which also includes the

Bureau of Justice Assistance, Bureau of Justice Statistics,

Office of Juvenile Justice and Delinquency Prevention, and

the Office for Victims of Crime.
1998 Annual Report on Marijuana Use iii

Acknowledgments

NIJ

K. Jack Riley, ADAM Director

Christine Crossland

Nora Fitzgerald

Tom Hay

Natalie Lu

Gerald Soucy

Bruce Taylor

ABT ASSOCIATES

Dana Hunt, Project Director

Phyllis Newton, Project Manager

Kyla Carrigan

Sarah Kuck

Quentin McMullen

Carol Putnam

William Rhodes

Tom Rich

George Yacoubian

Sylvia Young

DBA D ESIGN

Patricia L. Blake

Pearl Jusem

Jude Menz
1998 Annual Report on Marijuana Use v

Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Male Arrestee Marijuana Trends, 1990-98 . . . . . . . . . .4

Female Arrestee Marijuana Trends, 1990-98 . . . . . . . . .9

Marijuana Results by Age Cohort . . . . . . . . . . . . . . .13

Marijuana and the Use of Other Drugs . . . . . . . . . . .19

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Introduction

Levels of marijuana use among persons involved in the criminal justice system

are high; often one-third or more of the population has used marijuana within

days of an arrest (NIJ, 1998). In 1998 the percentage of adult male respondents

testing positive for marijuana use in the Arrestee Drug Abuse Monitoring

(ADAM) program ranged from a high of 53.1 percent in Oklahoma City to a

low of 24.8 percent in San Jose. For the 321sites that collected data on female

arrestees during 1998, the proportion of arrestees testing positive for marijuana

ranged from 37.9 percent in Seattle to 13.3 percent in Laredo. Within any

given site, men were generally more likely than women to test positive for marijuana in 1998. In addition, younger adults (15-20 and 21-25 years of age),

whether male or female, were the most likely to be involved with marijuana. 

Currently, 35 urban sites participate in the ADAM program. Twelve of the 35

sites were new to the ADAM system in 1998 and this report represents for

many the first look at rates of marijuana use in their arrestee populations. The

sites added to ADAM in 1998 are Albuquerque, Anchorage, Des Moines, Laredo, Las Vegas, Minneapolis, Oklahoma City, Sacramento, Salt Lake City, Seattle, Spokane, and Tucson. The lowest marijuana-positive rate for male arrestees

in a new site was reported in Las Vegas at 25.8 percent, and the lowest rate for

female arrestees in a new site was reported in Laredo, where females tested positive at the rate of 13.3 percent. Oklahoma City re p o rted the highest marijuanapositive rate for male arrestees in a new site (53.1 percent); for females, Seattle

reported the highest level (37.9 percent). In addition to Oklahoma City, Minneapolis (45.4 percent) and Sacramento (44.1 percent) reported high male marijuana-positive percentages among new sites. For females, Salt Lake City (29.4

percent) and Sacramento (28.2 percent) followed Seattle in reporting high

female marijuana use rates.

A comparison between 1997 and 1998 results in the 23 sites for which trend

data are available indicates that marijuana-positive percentages varied across

sites. Among all adult male arrestees, the median site rate of marijuana positives changed minimally, from 38.4 percent to 38.7 percent between 1997 and

1998 Annual Report on Marijuana Use 1

1 Atlanta had too few female cases for analysis purposes in 1998.
1998. For females, the site median remained essentially the same in 1997

(23.8) and 1998 (23.7). The most notable percentage point decreases for marijuana positives among adult males were in Atlanta (-10.1), Cleveland (-9.4),

Chicago (-6.9), and Omaha (-5.6). For females, the greatest percentage point

decreases were in Birmingham (-7.8 ), Detroit (-6.9), and Omaha (-5.1). The

largest percentage point increases for males were in Houston (+12.2), San

Antonio (+6.8), and New York City (+6.3). For females, the largest percentage

point increases in marijuana positives were in New Orleans (+10.5) and Wash2 1998 Annual Report on Marijuana Use

METHODOLOGY

To gauge drug use trends in urban areas,

the National Institute of Justice established the Drug Use Forecasting (DUF)

program in 1987. A modified version of

DUF, the Arrestee Drug Abuse Monitoring

(ADAM) program, was initiated in 1997.

To date, 35 jurisdictions participate in

ADAM. ADAM involves administration of a

survey instrument, which measures historical and current drug use patterns

among arrestees, and collection of a urine

sample which is tested for 10 drugs.

A more detailed overview of data collection methods can be found in the 1998

Annual Report on Drug Use Among Adult

and Juvenile Arrestees.

2 This box discusses how data collection methods have

affected reporting methods and two

significant reporting changes that will

appear in next year’s reports.

The first and most important change

relates to sampling. Data collected after

the mid-point of 1999 in all sites will be

collected under probability sampling

plans. This means that confidence intervals can be attached to estimates derived

from ADAM data which in turn means

that analysts can assess whether year-toyear changes in drug prevalence rates are

significant. For example, this year in New

York City, the cocaine prevalence for

males fell from 57.6 percent in 1997 to

47.1 percent in 1998. ADAM cannot

report that as a statistically significant

decline because of limits to the current

sampling plans. The 1999 reports will

introduce reporting on standard errors

and confidence intervals.

The second important change re l ates to

weighting the dat a . Each case collected

re p resents similar respondents (age, r a c e ,

and booking charge to name a few characteristics of interest) that we re not

selected for interv i ew. If a certain cat eg o ry of offender is re p resented out of

p ro p o rtion to the actual occurrence in

the arrest populat i o n , weighting can be

used to correct the dispro p o rt i o n a l i t y.

T h e re are numerous factors that introduce dispro p o rtion into the dat a . T h e

2 National Institute of Justice. (1999). “ADAM: 1998 Annual Report on Drug Use Among Adult and

Juvenile Arrestees.” Washington, D.C.: National Institute of Justice.
ington, D.C. (+9.2). It cannot be known whether these differences are significant because the samples are currently not selected using statistical methods

that would allow that computation (see “Methodology,” page 2).

Trend results may also be affected by a significant change to the ADAM marijuana drug testing protocol. In 1996 improvements in drug testing technology

led the U.S. Department of Health and Human Services to lower the detection

cutoff rate for marijuana from 100 nanograms (ng) per milliliter (ml) to 50

ng/ml. The impact of this change and additional analyses evaluating the impact

1998 Annual Report on Marijuana Use 3

jails included in the program have

changed over time, most recently as a

result of standardizing site cat c h m e n t

a reas at the county leve l . In add i t i o n , t h e

DUF program operated according to a

c h a rge priority system that emphasize d

i n t e rv i ewing and testing felony offenders

over misdemeanants. D rug offenders, w h o

a re more likely to test positive for dru g s

than their non-drug-offending counterp a rt s , we re limited to 20 percent of the

total sample to prevent drug offenders

f rom dominating the dat a . Traffic offenses

( e . g . , DUI and DWI) we re generally ex c l u ded from the sample. These practices we re

revised in the second quarter of 1998

d ata collection so that all arre s t e e s ,

reg a rdless of charg e , a re eligible for inclusion in the A DAM study.

This year’s data, as well as data collected

during previous years, could be weighted

by local arrest data to adjust for the

data collection methods. We chose not

to weight the data for two reasons.

First, there may be additional changes in

the data collection protocol this year

that would change the weighting process,

forcing us to revise the entire weighted

data series. Second, since confidence

intervals and quantification of uncertainty cannot be applied to the data series

until next year, it seemed appropriate to

do all of the design and reporting

changes in one year.

In add i t i o n , it is important that the current analysis be read with an understanding that the weighting and sampling issues

limit pre s e n t ation and interpre t at i o n . I n

p a rt i c u l a r, small changes from year to ye a r

in prevalence figures should not be viewe d

as definitive . It should be stressed that

the arrestee population is a difficult one

to access, and one not adequately cove re d

in other data collection efforts that , f o r

ex a m p l e , t a rget households, s c h o o l s , o r

t re atment populat i o n s . The data are most

i n f o r m at i ve over multiple years when

longer term trends can be discern e d .
on marijuana trend data are discussed in the 1996 Drug Use Forecasting (DUF)

Annual Report (NIJ, 1997). The lower cutoff level is expected to identify

greater numbers of occasional or moderate marijuana users. Thus, caution

should be used when comparing site results from 1996 forward with those from

previous years. Moreover, extra caution should be taken this year with comparisons with previous years because, as part of the ADAM program’s move toward

probability-based sampling at the county level, in some sites the sample expanded during the data collection year to include cases from additional jail facilities.

For example, in New York City the program is now operating in all 5 boroughs;

it previously operated only in Manhattan. 

Aggregate analysis of data may, in some cases, obscure important developments

in isolated or specific populations. Age, gender, and regional analyses of

ADAM data indicate that several developments are underway that point to the

need to monitor subgroups of marijuana users who could be overlooked within

the aggregate trends. These subgroups include younger arrestees, among whom

t h e re are signs of increasing marijuana use in some parts of the country; and

male arrestees whose marijuana use continues at high rates relative to those of

their female peers. A review of marijuana data generated by the DUF/ADAM

p rogram since 1990 provides a context within which these subtrends can be seen. 

Male Arrestee Marijuana Trends, 1990-98

Between 1990 and 1998, cocaine was generally the drug most likely to be

detected among both male and female participants, although there was substantial variation by both site and year. During the same period, marijuana was

generally the drug next most likely to be detected. In recent years, marijuana

use has grown to the point at which it is now the most prevalent drug used by

males in a majority of sites. In 1990 marijuana was the most commonly detected drug in 5 of 223

sites that collected data on males; in 1995 it was the most

common drug detected in males in 6 of 23 sites; and in 1998, it was the most

commonly detected drug in 22 of 35 sites among males and in 13 of the 23 vet4 1998 Annual Report on Marijuana Use

3 Miami did not begin data collection until 1991.
eran male sites. This pattern has not held among female arrestees, however.

Among females, marijuana was the most commonly detected drug in only one

of 20 sites collecting female data in 1990 and in none of the 32 sites collecting

female data in 1998.

Between 1990 and 1998, more than 180,000 adult male arrestees were surveyed

and drug tested as part of the ADAM program. For comparison purposes, each

ADAM site is assigned to one of five geographic regions: Northwest,

West/Southwest, Midwest, South, and Northeast. Marijuana increases vary by

region, with the largest increases found in the Midwest, South, and Northeast,

and the smallest in the West/Southwest region of the United States. Table 1

presents positive marijuana urinalysis results for adult male arrestees surveyed

through the ADAM program from 1990 to 1998 by site.

Over the 9-year period presented, all ADAM sites’ marijuana rates for males

increased with the exception of Portland, where levels decreased from 42.1 

percent in 1990 to 36.9 percent in 1998. Detroit, St. Louis, and Washington,

D.C. witnessed the largest percentage point increases of male marijuanapositive rates during the past nine years. For example, in 1990 the male marijuana-positive rate in St. Louis was 16.0 percent. By 1998, however, the male 

marijuana-positive rate increased to 50.2 percent, an increase of 34.2 percentage

points. In Detroit the rate increased from 15.2 percent in 1990 to 46.5 percent

in 1998. In Washington, D.C., the rate increased by 30.9 percentage points

over the 9-year period. Although it is not possible to know the standard error

of these figures, variations of this size suggest substantial changes. Of the 22

veteran sites collecting male data in 1990, San Jose re p o rts the lowest perc e n t a g e

point change (+0.9) between 1990 and 1998, followed by San Diego (+1.5), and

Phoenix (+4.7); Portland re p o rted a decrease of 5.2 percentage points, while the

remaining 18 sites re p o rted increases of between 7 and 34 percentage points.

In subsequent sections of this report, the data are discussed separately for the

years 1990 to 1995; 1995 to 1996; and 1996 to 1998. This is to ensure that percentage point increases that may be due solely to the modification in the drug

detection level (from 100 ng/ml to 50 ng/ml in 1996) are clearly illustrated. Of

1998 Annual Report on Marijuana Use 5
6 1998 Annual Report on Marijuana Use

Table 1. Percentage of Male Arrestees Testing Positive for Marijuana,

1990-98

1990 1991 1992 1993 1994 1995 1996 1997 1998

% % % % % % % % %

NORTHWEST

Anchorage* – – – – – – – – 33.3

Portland 42.1 32.4 27.8 29.5 26.7 28.7 35.0 38.2 36.9

Seattle* – – – – – – – – 35.4

Spokane* – – – – – – – – 42.9

WEST/SOUTHWEST

Albuquerque* – – – – – – – – 35.9

Denver 26.9 25.3 33.9 35.6 38.5 32.8 41.7 41.5 41.3

Laredo* – – – – – – – – 39.3

Las Vegas* – – – – – – – – 25.8

Los Angeles 19.6 18.7 22.9 23.0 19.6 22.8 29.5 26.5 27.3

Phoenix 27.5 22.0 22.1 31.1 28.8 29.2 28.4 30.4 32.2

Sacramento* – – – – – – – – 44.1

Salt Lake City* – – – – – – – – 36.8

San Antonio 26.1 20.3 28.5 32.0 29.5 33.7 39.1 34.3 41.1

San Diego 34.9 33.2 35.3 39.8 36.2 35.1 40.0 37.8 36.4

San Jose 23.9 25.2 24.5 27.2 29.8 26.8 26.9 28.9 24.8

Tucson* – – – – – – – – 39.2

MIDWEST

Chicago 26.8 23.1 26.2 40.1 38.2 40.6 47.0 48.4 41.5

Cleveland 14.0 11.8 17.2 23.1 27.5 29.3 37.5 46.2 36.8

Des Moines* – – – – – – – – 41.8

Detroit 15.2 18.5 26.7 36.7 37.6 41.5 45.5 44.0 46.5

Indianapolis 30.9 22.9 35.1 41.6 39.1 37.9 51.2 43.7 45.1

Minneapolis* – – – – – – – – 45.4

Omaha 20.2 25.6 38.2 42.0 44.3 42.0 51.9 49.5 43.9

St. Louis 16.0 16.0 21.2 28.3 36.4 39.4 51.9 48.4 50.2

* New site in 1998
the 22 sites collecting male data from 1990 to 1995, all but Portland witnessed

increases ranging from 0.2 to 27.7 percentage points in the marijuana-positive

rate. Seventeen sites reported increases greater than 5 percentage points. 

Six sites demonstrated increases in adult male marijuana positives of 20 

p e rcentage points or more from 1990 to 1995: Atlanta, Birmingham, Detro i t ,

Omaha, St. Louis, and Washington, D.C. In Atlanta the percentage of surv e y e d

male arrestees testing positive for marijuana increased from 3.8 percent in 1990

to 31.5 percent in 1995. In Detroit the percentage of male arrestees testing positive for marijuana increased from 15.2 percent in 1990 to 41.5 percent in 1995.

In Washington, D.C., marijuana positives for adult males increased from 7.1 

p e rcent in 1990 to 31.6 percent in 1995. St. Louis experienced a 23.4 perc e n t1998 Annual Report on Marijuana Use 7

1990 1991 1992 1993 1994 1995 1996 1997 1998

% % % % % % % % %

SOUTH

Atlanta 3.8 12.3 21.8 26.2 24.7 31.5 37.3 36.1 26.0

Birmingham 13.5 16.2 21.5 27.5 28.1 35.3 45.7 42.6 39.2

Dallas 20.4 19.5 28.0 27.5 32.7 37.0 44.1 43.5 43.1

Ft. Lauderdale 22.4 28.2 31.9 30.0 29.4 32.9 38.0 38.3 43.5

Houston 20.7 17.1 23.1 24.2 22.7 29.0 33.0 23.6 35.8

Miami – 22.6 30.0 25.9 27.7 29.2 34.2 31.5 29.2

New Orleans 17.7 15.7 19.0 24.9 28.4 32.1 39.9 38.4 38.3

Oklahoma City* – – – – – – – – 53.1

NORTHEAST

New York City 19.2 17.9 22.1 21.3 24.2 28.2 38.4 32.4 38.7

Philadelphia 18.2 18.1 26.3 32.3 32.3 34.2 38.7 41.3 44.9

Washington, D.C. 7.1 11.2 20.0 26.2 30.3 31.6 39.8 39.2 38.0

* New site in 1998
age point increase in male arrestees testing positive for marijuana between 1990

and 1995. Between 1990 and 1995, both Birmingham and Omaha reported a

21.8 percentage point increase in male marijuana positives.

The change in the cutoff level from 100 ng/ml to 50 ng/ml in 1996 was expected to cause a 5 to 7 percentage point increase in marijuana detections. Much of

this increase is because a 50 ng/ml cutoff detects more occasional and moderate

marijuana users. Given this caveat, four sites still experienced increases of 10

percentage points or more in adult male marijuana positives between 1995 and

1996: Birmingham, Indianapolis, New York City, and St. Louis. In Indianapolis

the rate for males increased from 37.9 percent to 51.2 percent. The St. Louis

male marijuana-positive rate increased from 39.4 percent in 1995 to 51.9 percent in 1996. In Birmingham the rate for males increased from 35.3 percent to

45.7 percent. In 1996 the adult male marijuana-positive rate for New York City

was 38.4 percent, a 10.2 percentage point increase from 28.2 percent in 1995.

The percentage of surveyed male arrestees testing positive for marijuana generally stabilized or decreased between 1996 and 1998. Of the 23 veteran sites, 16

had marijuana-positive rates for males in 1998 that were within 5 percentage

points of the rates in 1996. Five sites witnessed decreases greater than 5 percentage points in the rate of adult male marijuana positives between 1996 and

1998. In 1996 Miami’s marijuana rate was 34.2 percent, compared with 29.2

percent during 1998. Chicago’s male marijuana-positive rate dropped from

47.0 percent in 1996 to 41.5 percent in 1998. The Indianapolis male marijuana-positive rate decreased from 51.2 percent in 1996 to 45.1 percent in 1998.

In 1996 Birmingham’s male marijuana-positive rate was 45.7 percent, compared

with 39.2 percent in 1998. In Omaha the marijuana-positive rate for males

dropped eight percentage points from 51.9 percent in 1996 to 43.9 percent in

1998. Atlanta experienced the largest decrease (11.3 percentage points), from

37.3 percent in 1996 to 26.0 percent in 1998. Adult male marijuana-positive

rates increased in two sites between 1996 and 1998. In Philadelphia the rate

increased from 38.7 percent in 1996 to 44.9 percent in 1998. Ft. Lauderdale

8 1998 Annual Report on Marijuana Use
experienced a 5.5 percentage point rate increase in adult males testing positive

for marijuana, changing from 38.0 percent in 1996 to 43.5 percent in 1998.

Although the marijuana rate in most sites may have stabilized somewhat in 

the past three years, it nevertheless remains high, particularly among young

males. By the end of 1998, three sites for which trend data are available re p o rt e d

marijuana prevalence rates greater than 45 percent among males (Detroit, 

Indianapolis, and St. Louis). In addition, two new sites (Minneapolis and 

Oklahoma City) reported more than 45 percent of males testing positive for

marijuana in 1998. San Jose reported the lowest marijuana-positive rate 

among males in 1998 (24.8 percent), followed by Las Vegas at 25.8 percent. 

Female Arrestee Marijuana Trends, 1990-98

Between 1990 and 1998, nearly 70,000 adult female arrestees were surveyed and

drug tested as part of the DUF/ADAM program. Table 2 presents positive

marijuana urinalysis results for adult female arrestees surveyed through the

ADAM program from 1990 to 1998 by site.

Although female arrestees tested positive for marijuana less frequently than

their male counterparts, marijuana use still increased within the female arrestee

population. Over this 9-year period, all ADAM sites’ adult female marijuana

rates increased with the exception of Portland, where levels decreased from 26.8

percent in 1990 to 23.2 percent in 1998. Of the 21 veteran female collection

sites, San Jose reported the lowest percentage point change (+1.1) between 1990

and 1998. The remaining sites reported increases of between 6 and 22 percentage points. St. Louis and Washington, D.C. witnessed the largest increases

among females over the past 9 years. For example, the female marijuana-positive rate in St. Louis was 9.7 percent in 1990, but increased 22.2 percentage

points to 31.9 in 1998. In Washington, D.C., the 9-year rate increase among

female arrestees was 21.6 percentage points. 

1998 Annual Report on Marijuana Use 9
10 1998 Annual Report on Marijuana Use

Table 2. Percentage of Female Arrestees Testing Positive for Marijuana,

1990-98

1990 1991 1992 1993 1994 1995 1996 1997 1998

% % % % % % % % %

NORTHWEST

Anchorage* – – – – – – – – 23.1

Portland 26.8 27.8 16.8 17.2 19.4 16.4 25.9 19.0 23.2 

Seattle* – – – – – – – – 37.9 

Spokane* – – – – – – – – 26.8

WEST/SOUTHWEST

Albuquerque* – – – – – – – – 24.0 

Denver 15.1 16.5 19.0 24.3 22.1 21.1 26.7 31.5 29.9 

Laredo* – – – – – – – – 13.3 

Las Vegas* – – – – – – – – 21.6 

Los Angeles 10.1 9.4 12.6 15.1 12.3 13.5 20.4 17.9 21.8 

Phoenix 18.4 13.9 14.6 19.7 21.8 19.2 21.8 20.8 24.9 

Sacramento* – – – – – – – – 28.2 

Salt Lake City* – – – – – – – – 29.4 

San Antonio 8.9 9.0 15.6 16.2 14.8 15.5 18.6 17.3 17.5 

San Diego 19.1 20.0 24.7 25.4 19.8 19.6 23.2 23.8 26.7

San Jose 12.5 12.8 18.5 17.0 17.8 12.0 18.5 16.5 13.6 

Tucson* – – – – – – – – 21.5 

MIDWEST

Chicago – – – – – – – – 19.7 

Cleveland 8.0 7.1 11.0 13.4 15.7 11.0 22.0 22.1 27.0 

Des Moines* – – – – – – – – 15.2 

Detroit 9.1 3.6 10.6 10.6 16.2 17.6 18.6 28.4 21.5 

Indianapolis 20.8 21.8 26.3 25.4 22.2 23.8 31.0 29.9 31.2 

Minneapolis* – – – – – – – – 22.6 

Omaha – – – 22.2 28.3 23.8 32.8 33.3 28.2 

St. Louis 9.7 7.8 11.1 14.7 14.7 18.0 28.7 31.4 31.9 

* New site in 1998
Similar to the data for males, the results for females are discussed within the

context of the marijuana detection cutoff level change. Of the 20 sites that collected female data from 1990 to 1995, 18 reported increases in marijuana-positive rates between 0.5 and 11.8 percentage points. Nine sites experienced

increases among female arrestees greater than 5 percentage points from 1990 to

1995. In particular, two sites demonstrated increases in adult female marijuana

positives of 10 percentage points or more from 1990 to 1995: Atlanta and

Washington, D.C. In Atlanta the percentage of surveyed female arrestees testing positive for marijuana increased from 1.2 percent in 1990 to 13.0 percent in

1995. In Washington, D.C. marijuana positives for females increased from 6.9

percent in 1990 to 17.7 percent in 1995. 

1998 Annual Report on Marijuana Use 11

1990 1991 1992 1993 1994 1995 1996 1997 1998

% % % % % % % % %

SOUTH

Atlanta 1.2 7.6 12.9 15.5 14.9 13.0 25.9 27.7 –

Birmingham 8.2 9.6 12.6 12.1 16.8 12.0 22.4 25.4 17.6 

Dallas 17.8 11.0 23.8 19.2 22.5 21.4 26.8 27.5 24.2

Ft. Lauderdale 16.3 14.2 20.9 19.8 18.4 17.9 23.8 24.0 24.5 

Houston 11.0 8.6 11.7 14.9 12.9 17.8 26.2 16.7 20.1 

Miami – – – – – – – – –

New Orleans 11.7 7.3 8.6 13.8 7.4 16.2 13.5 11.6 22.1 

Oklahoma City* – – – – – – – – –

NORTHEAST

New York City 7.7 11.3 12.5 19.4 15.5 16.4 19.0 24.6 23.4 

Philadelphia 11.9 14.4 15.2 19.7 18.3 19.7 21.0 20.9 23.7 

Washington, D.C. 6.9 6.4 8.4 9.3 10.6 17.7 22.8 19.3 28.5 

* New site in 1998
Two sites collecting female data witnessed decreases in marijuana-positive

rates between 1990 and 1995. Portland experienced a 10.4 percentage point

drop between 1990 (26.8 percent) and 1995 (16.4 percent). In San Jose, the

female marijuana-positive rate decreased slightly from 12.5 percent in 1990 to

12.0 percent in 1995.

Again, the change in the cutoff level in 1996 is expected to cause a 5 to 7 percentage point increase in marijuana detection. Given this caveat, 4 sites still

experienced increases of 10 percentage points or more in adult female marijuana positives between 1995 and 1996: Atlanta, Birmingham, Cleveland, and

St. Louis. In Atlanta the rate for females increased from 13.0 percent to 25.9

percent. The Cleveland adult female marijuana-positive rate increased from

11.0 percent in 1995 to 22.0 percent in 1996. In St. Louis the rate increased

from 18.0 percent to 28.7 percent between 1995 and 1996. In 1996 the adult

female marijuana-positive rate for Birmingham was 22.4 percent, a 10.4 percentage point increase from 12.0 percent in 1995.

The percentage of surveyed female arrestees testing positive for marijuana

generally stabilized or increased slightly between 1996 and 1998, with the

exception of Houston. Of the veteran sites, 17 had marijuana-positive rates

for females in 1998 that were within 5 percentage points of the rates in 1996.

Two sites witnessed increases greater than 5 percentage points in the rate of

adult female marijuana positives between 1996 and 1998. In 1996 New

Orleans’s marijuana-positive rate was 13.5 percent compared with 22.1 percent during 1998. In Washington, D.C. the marijuana-positive rate increased

from 22.8 percent to 28.5 percent. The exception was Houston in which the

female marijuana-positive rate decreased 6.1 percentage points between 1996

and 1998, from 26.2 percent to 20.1 percent. 

Female arrestees have generally tested positive for marijuana at lower rates than

males. In 1990 marijuana-positive rates were lower for females than for males in

12 1998 Annual Report on Marijuana Use
all veteran ADAM sites collecting female data. In 1998, female marijuana rates

ranged from 6 to 25 percentage points lower than male positive rates in all veteran sites. Eleven of twelve new sites report male rates that are appreciably

higher than female rates. 

By the end of 1998, two sites retained marijuana-positive rates greater than 30

percent for females (Indianapolis and St. Louis). In addition, one site in its first

year of female arrestee data collection had more than 30 percent of the females

testing positive for marijuana in 1998 (Seattle, at 37.9 percent). In 1998 Laredo

reported the lowest rate of marijuana positives (13.3 percent) for females, 

followed by San Jose at 13.6 percent.

Marijuana Results by Age Cohort

The general assessment of marijuana rates presented above shows that marijuana use among adults has stabilized in the last three years in many sites. However, changes in drug use patterns among age groups, or cohorts, can be used to

anticipate future changes in overall drug use. Young users are particularly

important in this regard because, all other factors held constant, their presence

is likely to be felt in the community for longer than that of older drug users.

Thus, significant changes in drug use patterns among young adults should be

examined closely.

Recent analyses on marijuana use show that results vary by age group. For the

purposes of this discussion, age is reported in five categories: 15-20, 21-25, 26-

30, 31-35, and 36 and older. Of the 23 ADAM sites for which trend data are

available, 21 demonstrate patterns among young adult cohorts (ages 15-20) that

suggest marijuana use may be growing. Four factors are used to characterize

young adult marijuana use as potentially growing: a comparison of the 9-year

(1990-98) trend among young adults; a comparison of the 9-year (1990-98)

trend among young adults, adjusted for the detection cutoff level change in

1996; the 1997 to 1998 change among young adults; and the absolute level of

marijuana positives among young adults. Respectively, these factors provide

1998 Annual Report on Marijuana Use 13
information about long-term trends in the communities, recent changes in

communities, how large the initiation or new use cohort in the community is

likely to be, and the potential size of the initiation cohort relative to the existing magnitude of the problem.

From 1990 to 1998, marijuana use has changed from a pattern of concentration among older adults to domination of use by arrestees 25 years of age and

younger. Table 3 presents the percent of adult male and female arrestees

testing positive in the 234veteran ADAM sites for 1990 and 1998 by age

group. 

Among adult males, in 12 of 22 sites the reported 1990 marijuana-positive

rates for the two youngest cohorts (the 15-20 and 21-25 age groups) are at

least five percentage points greater than the rates for the three oldest age

cohorts. However, in 1998, in all 22 of the sites for which trend data are

available the highest marijuana prevalence rate occurred in those two age

groups. Females exhibit a similar trend of increasing prevalence among

younger users. In 1990 the results across female age cohorts were mixed.

Only 5 of 20 sites in 1990 showed the highest marijuana prevalence rates for

females among arrestees under age 25. However, in 1998, 21 of 22 sites

report the greatest percentage of marijuana positives in the female cohorts

under age 25.

Table 4 shows how extreme the difference in marijuana prevalence rates can

be between the younger and older age cohorts. Sites shown in Table 4 have,

at minimum, a 24 percentage point difference between the youngest cohort

(15-20 years of age) and the sites’ overall adult male positive rate for marijuana. The site with the largest difference, Chicago, experienced a 1998 overall

adult male positive rate of 41.5 percent. In contrast, Chicago’s youngest

cohort tested positive at 71.1 percent, a difference of 29.6 percentage points. 

14 1998 Annual Report on Marijuana Use

4 The analysis for Miami is based on an 8-year comparison because the site initiated data collection in

1991.
1998 Annual Report on Marijuana Use 15

Table 3. 1990 and 1998 Adult Male and Females Arrestees by Age Cohort

Testing Positive for Marijuana

SITE Adult Males

15-20 21-25 26-30 31-35 36+ Overall

% % % % % %

Atlanta 1990 4.5 7.7 1.3 4.3 2.7 3.8

1998 63.3 45.5 32.4 18.9 15.3 26.0

Birmingham 1990 15.6 20.6 12.3 13.5 5.1 13.5

1998 59.8 62.5 41.0 33.3 16.5 39.2

Chicago 1990 28.8 35.2 25.9 16.8 18.9 26.8

1998 71.1 54.9 37.0 30.9 20.7 41.5

Cleveland 1990 14.0 17.3 16.3 10.3 11.0 14.0

1998 68.6 58.5 39.8 28.3 14.8 36.8

Dallas 1990 25.5 27.9 19.4 16.8 10.1 20.4

1998 71.9 53.3 32.6 37.2 20.1 43.1

Denver 1990 27.5 37.0 29.8 22.2 18.9 26.9

1998 61.0 50.6 41.4 36.4 28.8 41.3

Detroit 1990 26.4 18.7 10.1 11.1 7.4 15.2

1998 74.8 62.9 39.8 34.5 19.7 46.5

Ft. Lauderdale 1990 30.0 34.3 22.9 18.3 11.0 22.4

1998 69.9 62.0 48.9 29.9 19.8 43.5

Houston 1990 27.3 25.3 18.6 19.8 11.8 20.7

1998 52.4 42.4 34.0 26.8 19.2 35.8

Indianapolis 1990 29.7 40.7 37.7 23.3 19.5 30.9

1998 76.6 60.2 40.5 37.2 32.5 45.1

Los Angeles 1990 24.3 27.4 23.3 15.8 9.8 19.6

1998 49.5 34.6 26.1 22.8 14.9 27.3

Miami* 1991 39.8 35.1 20.6 15.2 7.9 22.6

1998 45.2 37.5 36.4 27.6 12.5 29.2

New Orleans 1990 17.7 22.1 28.4 12.3 7.7 17.7

1998 61.6 45.5 36.9 26.5 23.1 38.3

New York City 1990 30.1 23.3 20.5 13.6 9.4 19.2

1998 67.9 53.2 38.7 33.2 20.2 38.7

Omaha 1990 20.9 25.6 16.0 19.0 17.0 20.2

1998 69.5 56.6 45.8 36.0 25.1 43.9

Philadelphia 1990 25.0 25.2 17.7 12.3 6.3 18.2

1998 70.9 55.1 40.4 23.4 18.3 44.9

*Miami did not begin collecting data until 1991.
16 1998 Annual Report on Marijuana Use

Table 3. 1990 and 1998 Adult Male and Females Arrestees by Age Cohort

Testing Positive for Marijuana (continued)

SITE Adult Males

15-20 21-25 26-30 31-35 36+ Overall

% % % % % %

Phoenix 1990 32.8 36.3 27.1 25.3 17.0 27.5

1998 54.9 44.6 29.8 23.4 23.0 32.2

Portland 1990 52.4 44.1 54.0 41.7 26.3 42.2

1998 58.8 57.0 40.8 30.3 23.6 36.9

St. Louis 1990 17.2 19.2 17.0 16.5 8.3 16.0

1998 74.4 56.3 44.8 36.3 23.5 50.2

San Antonio 1990 34.0 33.5 34.7 27.8 10.4 26.1

1998 58.6 48.3 34.7 33.6 22.1 41.1

San Diego 1990 38.2 42.4 34.3 32.8 23.8 34.9

1998 61.3 46.3 41.1 29.1 25.1 36.4

San Jose 1990 34.4 32.1 23.2 20.0 11.4 23.9

1998 36.0 28.8 21.6 19.4 19.7 24.8

Washington, D.C. 1990 8.5 8.2 8.3 7.3 3.9 7.1

1998 63.4 52.9 36.7 22.4 22.1 38.0

SITE Adult Females

15-20 21-25 26-30 31-35 36+ Overall

% % % % % %

Atlanta 1990 5.3 2.8 0.0 0.0 0.0 1.2 

1998 – – – – – –

Birmingham 1990 10.7 14.3 9.5 4.2 3.4 8.2 

1998 42.9 18.8 33.3 0.0 10.3 17.6 

Chicago 1990 – – – – – –

1998 13.3 38.1 27.3 16.7 12.2 19.7 

Cleveland 1990 9.5 12.1 5.8 11.1 0.0 8.0 

1998 83.3 45.5 18.2 35.7 4.8 27.0 

Dallas 1990 25.5 11.7 19.2 16.4 19.6 17.8 

1998 19.4 37.2 23.4 21.4 19.3 24.2 

Denver 1990 11.4 20.2 16.0 11.4 10.7 15.1 

1998 47.6 41.4 24.4 27.5 23.1 29.9 
1998 Annual Report on Marijuana Use 17

SITE Adult Females

15-20 21-25 26-30 31-35 36+ Overall

% % % % % %

Detroit 1990 6.1 12.0 5.0 10.1 12.1 9.1

1998 40.0 38.5 20.0 11.8 15.8 21.5 

Ft. Lauderdale 1990 16.7 23.3 23.6 12.4 4.4 16.3 

1998 33.3 30.6 25.9 23.6 19.6 24.5 

Houston 1990 13.0 13.9 10.6 9.3 7.2 11.0 

1998 19.6 29.2 21.9 16.4 13.2 20.1 

Indianapolis 1990 16.4 18.2 30.5 16.7 18.0 20.8 

1998 48.6 47.8 27.1 25.9 22.3 31.2 

Los Angeles 1990 16.4 11.6 10.4 10.6 4.1 10.1

1998 47.4 26.8 22.9 21.1 14.4 21.8 

New Orleans 1990 11.1 15.7 14.4 5.9 9.9 11.7 

1998 35.4 20.0 28.2 17.7 17.1 22.1 

New York City 1990 7.7 9.3 12.1 4.2 3.6 7.7

1998 43.1 45.1 20.7 22.9 14.5 23.4 

Omaha 1990 – – – – – –

1998 28.6 38.1 26.9 28.0 22.6 28.2 

Philadelphia 1990 4.2 18.5 12.4 11.5 6.6 11.9 

1998 45.0 31.6 21.3 23.9 14.5 23.7 

Phoenix 1990 25.0 20.6 20.6 15.4 10.6 18.4 

1998 51.9 34.8 20.0 15.4 17.2 24.9 

Portland 1990 20.0 31.0 33.8 26.2 17.2 26.8 

1998 48.5 31.0 15.4 19.6 17.9 23.2 

St. Louis 1990 7.7 12.3 10.5 8.7 7.1 9.7 

1998 40.0 54.8 19.4 28.1 20.5 31.9 

San Antonio 1990 4.1 7.8 9.0 20.6 2.9 8.9 

1998 16.5 24.1 16.9 21.2 9.6 17.5

San Diego 1990 26.5 19.1 20.5 13.1 20.6 19.1 

1998 25.0 41.3 25.6 21.1 23.6 26.7 

San Jose 1990 9.7 14.6 11.3 14.8 10.2 12.5 

1998 14.3 13.3 25.0 12.9 6.8 13.6 

Washington, D.C. 1990 3.7 14.1 4.7 4.6 3.2 6.9 

1998 63.0 47.1 15.4 22.2 14.0 28.5 
Sites new to ADAM in 1998 exhibited similar patterns of higher levels of

marijuana positives within the youngest age cohort of arrestees. Table 5 

presents the percentages of arrestees testing positive for marijuana for select

age cohorts at all new sites. Of the 12 new sites, 10 reported levels of use

among the 15- to 20-year-old cohort that are at least 20 percentage points

above the adult male site average. The most substantial difference is in 

Las Vegas, with 64.0 percent of the youngest adult male arrestees testing

positive for marijuana compared with 25.8 percent of all Las Vegas adult

males surveyed. One site varied slightly from this pattern, although use was

still concentrated among young users (under 25 years of age). In Anchorage

the highest marijuana-positive rate (54.5 percent) was found among 21- to

25-year-olds. 

Adult female marijuana users tend to be concentrated in an older age cohort

than their male counterparts. Instead of the rate being driven by the 15- to

20-year-old category, the highest marijuana prevalence rates for females fell

in the 21-25 year age category for most of the sites. For example, in 1998 

19.4 percent of the youngest females in Dallas tested positive, but 37.2 percent of 21- to 25-year-old females tested positive.

18 1998 Annual Report on Marijuana Use

Table 4. Select 1998 Adult Male and Female Arrestees Testing Positive for 

Marijuana

SITE Adult Males Adult Females

15-20 21-25 Overall 15-20 21-25 Overall

% % % % % %

Chicago 1998 71.1 54.9 41.5 13.3 38.1 19.7

Dallas 1998 71.9 53.3 43.1 19.4 37.2 24.2

Detroit 1998 74.8 62.9 46.5 40.0 38.5 21.5

Indianapolis 1998 76.6 60.2 45.1 48.6 47.8 31.2

Philadelphia 1998 70.9 55.1 44.9 45.0 31.6 23.7

St. Louis 1998 74.4 56.3 50.2 40.0 54.8 31.9
Marijuana and the Use of Other Drugs

Alcohol is reported as the substance most used in conjunction with marijuana, but there are a number of reports of marijuana combined with powdered

cocaine, crack cocaine, methamphetamine, and PCP (ONDCP, 1997; NIDA,

1998). Between 1990 and 1998, among arrestees testing positive for marijuana, 40.0 percent also tested positive for cocaine, 7.2 percent for opiates, 7.0

percent for methamphetamine, and 3.2 percent for PCP. Table 6 displays

cocaine-, methamphetamine-, and PCP-positive results by site for those

arrestees testing positive for marijuana in 1998.

Given the large percentage of marijuana positive arrestees who also test 

positive for both marijuana and cocaine (40.0 percent) in all sites, it is not

1998 Annual Report on Marijuana Use 19

Table 5. Percentage of 1998 Male Arrestees Testing Positive for Marijuana by

Select Age for New ADAM Sites

SITE Adult Males

15-20 21-25 Overall

% % %

Albuquerque 56.9 42.2 35.9

Anchorage 40.0 54.5 33.3

Des Moines 68.4 54.8 41.8

Laredo 62.1 47.6 39.3

Las Vegas 64.0 35.4 25.8

Minneapolis 76.5 53.8 45.4

Oklahoma City 87.3 67.6 53.1

Sacramento 69.7 65.1 44.1

Salt Lake City 42.5 35.4 36.8

Seattle 60.4 51.2 35.4

Spokane 71.7 51.8 42.9

Tucson 63.0 51.3 39.2
20 1998 Annual Report on Marijuana Use

Table 6. 1998 Marijuana Positive Results by Other Drug Positives

SITE Cocaine Methamphetamine PCP

% % %

NORTHEAST

New York City 40.7 0.0 1.0

Philadelphia 39.2 0.9 16.6

Washington, D.C. 23.6 0.0 4.6

SOUTH

Atlanta 48.8 0.0 0.0

Birmingham 41.8 0.0 0.0

Dallas 27.4 5.6 6.6

Ft. Lauderdale 49.1 0.0 0.0

Houston 40.9 0.4 13.4

Miami 55.3 0.0 0.0

New Orleans 50.9 0.7 0.0

Oklahoma City 27.5 11.5 5.0

MIDWEST

Chicago 40.0 0.2 3.9

Cleveland 35.7 0.0 10.8

Des Moines 15.2 20.3 1.3

Detroit 21.8 0.4 0.0

Indianapolis 36.5 0.8 0.8

Minneapolis 29.1 0.6 0.6

Omaha 31.3 15.8 0.6

St. Louis 31.6 0.8 1.4

WEST/SOUTHWEST

Albuquerque 51.6 4.8 0.0

Denver 42.1 6.9 0.0

Laredo 59.5 0.0 0.0

Las Vegas 17.8 19.6 5.6

Los Angeles 44.6 10.3 3.6

Phoenix 30.9 25.7 3.4

Sacramento 15.9 27.6 0.4

Salt Lake City 22.0 29.0 0.0
surprising that there is little regional variation. Four sites report that more

than 50 percent of those testing positive for marijuana also test positive for

cocaine (Albuquerque, Laredo, Miami, and New Orleans). San Jose reports the

lowest rate of concurrent cocaine and marijuana use (7.8 percent). There are

differences in the concurrent use of marijuana and methamphetamine, however,

reflecting where amphetamines and methamphetamine are prevalent. In the

West/Southwest, San Diego reported the highest methamphetamine-positive

rate (39.9 percent) among those arrestees who tested positive for marijuana. In

the South, Oklahoma City reported the highest methamphetamine-positive rate

(11.5 percent) among marijuana users, and in Portland, 26.1 percent of arrestees

tested positive for both marijuana and methamphetamine, the highest rate

among the Northwest sites.

1998 Annual Report on Marijuana Use 21

SITE Cocaine Methamphetamine PCP

% % %

WEST/SOUTHWEST (continued)

San Antonio 39.6 3.2 0.2

San Diego 20.5 39.9 2.6

San Jose 7.8 31.3 3.1

Tucson 49.2 7.8 0.0

NORTHWEST

Anchorage 45.7 0.0 0.0

Portland 25.5 26.1 0.6

Seattle 38.8 7.5 1.3

Spokane 19.1 18.5 0.6
Conclusions

Results from ADAM are consistent with drug use trends in other drug surveys

in different populations. The National Household Survey on Drug Abuse

(NHSDA), Monitoring the Future (MTF), and the Drug Abuse Warning Network (DAWN), along with Pulse Checkand the Community Epidemiological

Work Group (CEWG), have all shown marijuana use slowly increasing or stabilizing. However, the prevalence of marijuana use among arrestees is greater

than in other populations. In 29 of the 35 ADAM sites, at least one-third of all

adult male arrestees tested positive for marijuana in 1998. In 26 of 32 sites collecting female data, at least one-fifth of females tested positive for marijuana.

These aggregate findings, however, tell only a portion of the story.

In many ADAM sites, marijuana use is not only concentrated among those

arrestees under 25, but is also growing most rapidly in those age groups. Nine

sites report that 70 percent or more of their male arrestees 15-20 years old tested positive for marijuana in 1998. Use levels for females are somewhat lower

than for males and the highest prevalence rates are more likely to occur among

the 21- to 25-year-old cohort. Nevertheless, the high rates of marijuana use

among young adults, particularly males, suggest communities will be confronting marijuana use well into the foreseeable future. To the extent that

young adults continue their marijuana use into and beyond their thirties, communities should be prepared to expect large marijuana-using cohorts for many

years to come. 

The 1998 ADAM results also show that other drugs are routinely used with

marijuana. Cocaine and alcohol are the most common drugs used with marijuana, although substantial variations are seen with other drugs by site. For

example, in areas such as the Southwest, where methamphetamine is prevalent,

concurrent use of marijuana and methamphetamine is also prevalent. In areas

where PCP is used, PCP is also found with marijuana. 

22 1998 Annual Report on Marijuana Use
Combined, marijuana’s prevalence and the degree to which it is concentrated

among younger cohorts raise a longer term issue to which communities should

be sensitive. If substantial portions of marijuana users become regular users of

other drugs, the declines in other drug use that have been achieved (see 1998

Annual Report on Cocaine Use Among Ar restees5) could be reversed. In other

words, since many individuals do not report trying drugs other than marijuana

until their late teens and early twenties, and since marijuana use is concentrated

among young adults, there is some risk that what is now primarily marijuana

use among young adults may spread to include other drugs. With such a lagged

effect, communities may begin to confront increases in other drug use among

arrestees in the coming years. The available information on poly-drug use

clearly demonstrates that marijuana users do not confine their drug use to marijuana. Whether use of other drugs with marijuana will become a more prominent pattern in the future is not clear. However, the size of the marijuana-using

cohort, in conjunction with its concentration among arrestees whose drug use

patterns may not be fully developed, suggests that this potential should be carefully monitored. 

1998 Annual Report on Marijuana Use 23

5 National Institute of Justice. (1999). “1998 Annual Report on Cocaine Use Among Arrestees.” Washington, D.C.: National Institute of Justice.
References

National Institute of Justice. (1997). “1996 Drug Use Forecasting (DUF):

Annual Report on Adult and Juvenile Arrestees.” Washington, D.C.: National Institute of Justice.

National Institute of Justice. (1998). “ADAM: 1997 Annual Report on Adult 

and Juvenile Arrestees.” Washington, D.C.: National Institute of Justice.

National Institute on Drug Abuse. (1998). “Epidemiologic Trends in Drug Abuse:

Papers Presented at the Community Epidemiology Work Group 

Meeting in Boston, MA, June 1998.” Washington, D.C.: National Institute 

on Drug Abuse.

Office of National Drug Control Policy. (1997). “Pulse Check, Trends in Drug

Use: Spring-Fall 1996.” Washington, D.C.: U.S. Government Printing Office.

24 1998 Annual Report on Marijuana Use
For Information on the National Institute of Justice, please contact:

National Criminal Justice Reference Service

P.O. Box 6000

Rockville, Maryland 20849-6000

(800) 851-3420

(301) 519-5500

E-mail: askncjrs@ncjrs.org

You can view or obtain an electronic version of this 

document from the NIJ World Wide Web site. 

To access the site, go to http://www.ojp.usdoj.gov/nij

If you have any questions, call or e-mail NCJRS.