Illicit drug use among population ages 12 and older is derived from the National Survey on Drug Use & Health (NSDUH), which is the primary source of statistical information on the use of illegal drugs by the U.S. population. The survey is sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA). The NSDUH collects information from residents of households, non-institutional group quarters (e.g., shelters, rooming houses, dormitories), and civilians living on military bases. Persons excluded from the survey include homeless persons who do not use shelters, active military personnel, and residents of institutional group quarters, such as jails and hospitals.
A small subset of data from NSDUH is available on PeriStats, and includes the percent of the population ages 12 and older that engage in illicit drug use. To ensure reliability, data are provided for a 2-year combined period. Illicit drug use indicates past month use at least once of marijuana/hashish, cocaine (including crack), inhalants, hallucinogens (including PCP and LSD), heroin, or any prescription-type psychotherapeutic used non-medically. More background is available at the NSDUH Web site.