Marijuana Access and Adult Use

Washington State passed Initiative 502 (I-502) in November 2012, legalizing recreational marijuana for adults aged 21 and older. In July 2014, retail sales began with a great deal of variation in accessibility across the State. Previous research predicts that greater availability due to legalization will lead to more use of the drug, however studies estimating the impact of local access to recreational marijuana are lacking. We use the 2014, 2015, and 2016 Behavioral Risk Factor Surveillance System (BRFSS) for Washington to examine the impact of local access to retail marijuana on adult use. Our two main outcome measures are if a respondent used marijuana in the past month and the number of days they used it in the past 30. Using a difference-in-differences framework based on geographic information systems (GIS) measures of travel time to the nearest retailer and retail density, we find that as retailers are closer to where they live, more individuals use marijuana and more frequently. Retail density does not impart an effect on past-month use. In addition to the main sample, we stratify the data by sex and age. Our subgroup results indicate that use by women and individuals aged 18-26 increases at both the extensive and intensive margins as the drive time to the nearest retailer decreases. Individuals aged 65 and over also use more frequently as retailers get closer. We believe that this analysis may help inform policymakers in the crafting of future recreational marijuana laws to avoid potentially negative impacts on public health.