How State Policies Shape College Students' Cannabis and Alcohol Use

Cannabis policies differ between states that have legalized cannabis use, and within states over time following legalization milestones. A continuous measure of state cannabis policy environments was examined in relation to college students' cannabis and alcohol use, accounting for concurrent state alcohol policies. Undergraduates (n=902,486) ages 18-24 years from 591 four-year institutions in 47 states completed a cross-sectional survey between 2008 and 2019. Time-varying, state-level Cannabis Policy Scale (CPS) and Alcohol Policy Scale (APS) scores were sums of 17 and 29 policies, respectively, weighted by efficacy and state-level implementation. Outcomes were any 30-day use and frequent use (20+ days) of cannabis and alcohol, 2-week binge drinking (5+ drinks in a sitting), and co-use (binge drinking and frequent cannabis use). Data were analyzed in 2024-2025. Higher CPS scores (greater restrictiveness) were associated with significantly lower odds of cannabis use, frequent cannabis use, and co-use [OR=0.97 (0.96-0.98); 0.93 (0.91-0.94); and 0.94 (0.92-0.96), respectively], but not significantly associated with alcohol use outcomes. Higher APS scores were significantly associated with lower odds of every cannabis, alcohol, and co-use outcome. CPS and APS effects generally were significant for underage students (ages 18-20), but stronger for older students (ages 21-24). Under less restrictive state cannabis and alcohol policy regimes college students were more apt to use cannabis and alcohol frequently and concurrently. To improve students' well-being, campus- and community-level policymakers can build on strong state policy environments or compensate for weak ones, using APS and CPS as tools to identify these needs.