Marijuana legalization and traffic fatalities revisited

Abstract

The legal landscape for marijuana in the United States has changed dramatically over the last three decades. While several studies have examined the relationship between marijuana legalization and traffic fatalities, some of the research is becoming outdated and existing evidence remains mixed. Our research revisits the topic with two updates. First, our study includes states that legalized marijuana more recently and provides updated evidence on the effects of marijuana legalization. Second, considering recent discussions about the limitations of difference‐in‐differences designs, we employ alternative estimators that are robust to heterogeneous and dynamic treatment effects. Overall, our alternative estimators suggest either a smaller reduction (i.e., 3.9% drop in the overall fatality rate) or no change in traffic fatalities associated with legalizing marijuana for medical use, compared to the two‐way fixed‐effect estimator. We find no significant impact on traffic fatalities associated with legalizing marijuana for recreational use.