Cannabis and Vaping Rose After Legalization, But Cigarette Use Did Not

Using difference-in-differences analysis of 171,257 observations from 55,406 individuals, recreational cannabis legalization was associated with a 3.28 percentage point increase in cannabis use and 1.39 percentage point increase in ENDS use compared to control states. Cigarette use did not significantly change (-0.99 points). Cannabis use increased more after retail outlets opened (3.74 points) than before (1.17 points).

Difference-in-differences analysis of the nationally representative Population Assessment of Tobacco and Health (PATH) longitudinal cohort study (2013-2022), comparing states with recreational cannabis legalization to control states over 5 years.

This is one of the first studies with enough follow-up to show longer-term effects of cannabis legalization on both cannabis and tobacco product use, using a rigorous causal inference design.

The finding that legalization increases cannabis use but not cigarette use addresses a key policy concern. The unexpected increase in e-cigarette use suggests cross-product effects that regulators should monitor, potentially driven by vaping hardware crossover.

Observational design despite difference-in-differences approach. State-level variation in implementation complicates uniform analysis. Self-reported use. Does not capture frequency or quantity changes within users. Cannot identify which individuals are new users versus increased users.