The Kids Aren't Alright

We exploit shocks to US federal enforcement policy to assess how legal medical marijuana market size affects youth marijuana use and consequences for youth traffic-related fatalities. Using hand-collected data on state medical marijuana patient rates to develop a novel measure of market size, we find that legal market growth increases youth marijuana use. Likely mechanisms are lower prices and easier access. Youth die more frequently from alcohol-involved car accidents, suggesting complementarities for youths. The consequences of marijuana legalization for youth are not immediate, but depend on how supply-side regulations affect production and prices.