PROJECT SUMMARY/ABSTRACT Despite federal cannabis prohibition, an increasing number of states are implementing or considering cannabis legalization. Washington and Oregon were among the first states to legalize, in 2012 and 2014. Jurisdictions in the U.S. and abroad are looking to the early state adopters to identify best practices for state and local policy, and to learn about the impact of cannabis legalization beyond the short-term. In response to state legalization of recreational cannabis, many communities in Washington and Oregon have initiated additional regulatory policies or taxes. Currently, there is no evidence base to predict the effectiveness of such local policy actions for moderating public health or social outcomes that may follow cannabis legalization. The Aims of the proposed study are to: 1) Monitor and document local-level changes in cannabis policies, prices, and market activities (e.g., density, sales) in Oregon and Washington. 2) Assess how local variation in cannabis policies, prices, and market activities in Oregon and Washington affect cannabis use and related health outcomes beyond the short-term (5-10 years after legalization) among youth, pregnant and parenting women, and adults. 3) Estimate the short-term and longer-term effects of local-level cannabis policies, prices and market activities on the prevalence and frequency of alcohol and tobacco use among youth, pregnant women, new mothers, and all adults, as well as substance use treatment and hospitalizations related to alcohol and opioids in Oregon and Washington. We will address these aims using quasi-experimental methods and geospatial analyses that exploit within-state and across-time variation in cannabis policies, prices, and market activities. We will collect and review local marijuana policies in both states, retailer-level licensing and transaction data, and assess their association with relevant behavioral, public health and social outcomes. We will rely on multiple established public health surveillance and other data reporting systems, which are largely common across both states. Findings from this study will provide policymakers and other stakeholders with strong evidence about the effectiveness of local cannabis policies on public health outcomes.