“As US states move toward various forms of adult access to cannabis, there has been a great interest in measuring the impact of such changes on adolescent cannabis use.
Using the Washington Health Youth Survey, we estimate that after recreational cannabis legalization past 30-day cannabis use prevalence in grade 8 decreased by 22.0%, in grade 10 prevalence decreased by 12.7%, and no effect in grade 12.
These trends are consistent with those in states without recreational cannabis laws, suggesting that legalization did not impact adolescent use prevalence.”
https://www.ncbi.nlm.nih.gov/pubmed/31792712
https://link.springer.com/article/10.1007%2Fs11121-019-01068-4