Alcohol, Marijuana, and American Youth: The Unintended Effects of Government Regulation

This paper analyzes the impact of increases in the minimum drinking age on the prevalence of alcohol and marijuana consumption among high school seniors in the United States. The empirical analysis is based on a large sample of students from 43 states over the years 1980- 1989. We find that increases in the minimum drinking age did reduce the prevalence of alcohol consumption. We also find, however, that increased legal minimum drinking ages had the unintended consequence of increasing the prevalence of marijuana consumption. We estimate a model based on the canonical theory of the consumer. Estimates from this model suggest that this unintended consequence is attributable to standard substitution effects. The estimates of the structural model also suggest that an increased drinking age helps create a climate of societal disapproval for all drug use, not only alcohol. We find that holding the consumption of alcohol constant, an increase in the drinking age reduces the prevalence of marijuana consumption. This effect is not large enough, however, to offset the large substitution toward marijuana induced by the decreased prevalence of alcohol consumption.