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Canada, Uruguay, and 18 states in the U.S. have legalized the use of nonmedical (recreational) cannabis for adults, yet the impact of legalization on adolescent cannabis use remains unclear. This study examined whether cannabis legalization for adults predicted changes in the probability of cannabis use among adolescents aged 13–18 years.


Data were drawn from 3 longitudinal studies of youth (spanning 1999–2020) centered in 3 U.S. states: Oregon, New York, and Washington. During this time, Oregon (2015) and Washington (2012) passed cannabis legalization; New York did not. In each study, youth average age was 15 years (total N=940; 49%–56% female, 11%–81% Black/African American and/or Latinx). Multilevel modeling (in 2021) of repeated measures tested whether legalization predicted within- or between-person change in past-year cannabis use or use frequency over time.


Change in legalization status across adolescence was not significantly related to within-person change in the probability or frequency of self-reported past-year cannabis use. At the between-person level, youth who spent more of their adolescence under legalization were no more or less likely to have used cannabis at age 15 years than adolescents who spent little or no time under legalization.


This study addresses several limitations of repeated cross-sectional studies of the impact of cannabis legalization on adolescent cannabis use. Findings are not consistent with changes in the prevalence or frequency of adolescent cannabis use after legalization. Ongoing surveillance and analyses of subpopulations are recommended.

Section snippets


Despite its importance as a policy shift and widespread adoption by states, research on the impact of nonmedical cannabis legalization for adults (legalization for brevity) is in its early stages. Early onset, frequent, heavy, or prolonged cannabis use during adolescence is associated with difficulties with academic performance and attainment, social relationships, depression, suicidal thoughts and behaviors, substance use disorder, and poorer adult functioning.1, 2, 3, 4 Thus, possible

Study Sample

Participants in 3GS were the children of men in the longitudinal Oregon Youth Study (OYS). Participants’ fathers were originally recruited to OYS as boys in 1983–1985 from fourth-grade classes of schools in neighborhoods of a midsized Oregon City with higher than city-average rates of juvenile arrests. Beginning in 2005, OYS men who became fathers were invited to participate in 3GS with their first 2 biological children by each mother (i.e., a participant with 2 children each with 2 women might


Table 1 shows the sample sizes and prevalence/frequency of cannabis use, legalization, and years lived in a legal state by age and study. Cannabis use prevalences across ages are comparable with state-specific data from the 2018–2019 National Survey on Drug Use and Health.21

There was a high degree of within-person dependence in past-year cannabis use across observations (intraclass correlation=0.532 in the grand-mean-only model). Tables 2 and 3 show the results for the dichotomous past-year


This study integrated longitudinal data from 3 studies of youth centered in 3 states—2 that adopted cannabis legalization early on and 1 that did not—to examine whether legalization predicted changes in the probability or frequency of past-year cannabis use among adolescents. A novel contribution of this study was the attempt to disentangle within-person versus between-person changes in cannabis use after legalization. Thus, it was assessed whether legalization coincided with a higher or lower


Several limitations should be considered when interpreting this findings. The included samples were not state representative; although the focal youth themselves lived in a broad range of neighborhood contexts, their parents were participants in studies that oversampled youth who lived in relatively higher-crime neighborhoods in their respective cities in the 1980s. Higher-crime and lower SES communities are important to study because they often experience disproportionate legal consequences


The rates of adolescent cannabis use may be holding steady after nonmedical cannabis legalization for adults, but ongoing surveillance is recommended. Future studies should examine the potential differences in the impact of legalization across demographic groups. Given the impacts of legalization on increased cannabis use by parents,8 future studies should consider whether children of parents who use cannabis are more susceptible to legalization impacts than children of parents who abstain.


The authors gratefully acknowledge the generosity of the participants in our studies. The authors also thank Sally Schwader and Tanya Williams for editorial assistance.

Points of view reflect those of the authors and not of the funding agency. The funding agency had no role in the design of the study, data collection or analysis, interpretation of results, or the decision to submit this manuscript for publication.

This study was supported by funding from the National Institute on Drug Abuse


Jennifer A. Bailey: Conceptualization, Data curation, Funding acquisition, Methodology, Project administration, Writing–original draft. Stacey S. Tiberio: Conceptualization, Formal analysis, Methodology, Visualization, Writing–original draft. David C.R. Kerr: Conceptualization, Funding acquisition, Methodology, Project administration, Writing–review and editing. Marina Epstein: Conceptualization, Project administration, Methodology, Writing–review and editing. Kimberly L. Henry:


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