Frequent cannabis use among California 11th graders increased after retail legalization, especially where new stores opened

Frequent cannabis use among 11th graders increased post-retail legalization. Any past-30-day use initially rose then slowly declined, except in jurisdictions newly allowing storefront and delivery retail, where elevated rates persisted. Cannabis use was consistently lower in jurisdictions that banned retail and lacked pre-existing medical sales.

Adjusted interrupted time-series multilevel models analyzed cross-sectional data from the 2015/2016 to 2019/2020 California Healthy Kids Surveys (n=377,205 11th graders). Changes in past-30-day and frequent cannabis use were assessed pre- and post-retail legalization, stratified by local city and county cannabis retail policies.

This is one of the largest studies examining how local cannabis retail policies affect youth use. The finding that local bans were associated with lower use, while new retail access sustained higher rates, has direct implications for communities making zoning decisions.

This study bridges the gap between state-level legalization research and local policy effects. It suggests that while statewide legalization sets the legal framework, local retail decisions meaningfully shape youth exposure and use patterns.

Cross-sectional survey design cannot track individual students over time. Self-reported data subject to social desirability bias. Data ends spring 2020, so pandemic effects are a potential confounder. Pre-existing community norms likely influenced both local policies and baseline use rates.