Introduction

Marijuana use has received considerable attention by policymakers and researchers because it continues to be the most widely used illicit drug in this country. In 1997, approximately 80% of current illicit drug users were marijuana or hashish users (OAS, 1998c, p.16). NHSDA data also show that marijuana was the most commonly used illicit drug (see Table 2.1), with approximately 71 million (or 33%) of individuals aged 12 or older in the United States reporting marijuana use in their lifetime, 19 million (or 9%) reporting use in the past year, and 11 million (or 5%) reporting current use (i.e., past month use). As indicated in the Chapter 2 tables, the percentage of persons reporting marijuana use has remained relatively stable since 1988. The only exception occurred among adolescents, among whom marijuana use increased steadily between 1992 and 1997. In 1996, 13% of youths aged 12 to 17 had used marijuana in the past year and 7% had used in the past month; in 1997, those numbers increased to 16% and 9%, respectively.

Other studies of adolescents have found similar trends (Johnston, O'Malley, & Bachman, 1998a, 1998b; National Clearinghouse for Alcohol and Drug Information [NCADI], 1998). An estimated 2.5 million Americans used marijuana for the first time in 1996 (the year prior to the 1997 survey), as did about the same number in 1995 (OAS, 1998c, Table 38). The number has been increasing since 1991, after a long-term decrease that had been occurring since 1975. The rising incidence during the 1990s seems to have been fueled largely by the increasing rate of new use among youths aged 12 to 17 (from 37 per 1,000 person years in 1991, to about 54 per 1,000 person years in 1993, to about 83 per 1,000 person years in 1996) (OAS, 1998c, Table 38). Although the rates of new use among young adults also have increased, these increases have not been as dramatic.

This chapter discusses the prevalence and correlates of marijuana and hashish use. The following sections provide a detailed description of the prevalence of marijuana use in demographic subgroups defined by age, gender, race/ethnicity, population density, region, adult education, and current employment status. This chapter also discusses the frequency of marijuana use, the relationships between use of marijuana and other drugs, and information on who respondents used marijuana with and why they used marijuana.