New Report: Legalizing Marijuana Hasn’t Made Roads Less Safe

• In California, Maine, Massachusetts, and Nevada – four states that fully legalized marijuana in 2016 – traffic fatalities declined or remained the same in the three years that followed, compared to a slight increase in states where it remained illegal.
• A comprehensive study of traffic data in the U.S. and Canada failed to find a statistically significant change in accidents and fatalities after legalization.
• Alcohol, which remains fully legal in all 50 states and D.C., is a factor in nearly a third of all automotive fatalities.

Each year, more states are added to the list of those that are legalizing marijuana for medical and recreational use. Currently, the federal government is considering “rescheduling” the plant – a move that wouldn’t legalize it entirely, but would be a step in that direction. With voters in several states considering legalization this year at the ballot box, we wanted to know whether states that have legalized in the past have seen their roads become less safe as a result.

Our team studied car accident data in states throughout the country before and after they legalized marijuana to see if legalization correlated with higher accident rates. We also spoke to state officials to gain their perspective on the effects of legalization on their roads.

For clarity and consistency, we chose four states – California, Maine, Massachusetts, and Nevada – that fully legalized marijuana in 2016 to study vehicle death rate trends. We used deaths per 100,000,000 vehicle miles as our primary metric,sourced from the National Safety Council (NSC). Our team examined individual vehicle death rates and aggregated fatality rates in these four states during the years following 2016 and compared them to the U.S. national average. We also compared these numbers with those of Idaho, Indiana, Kansas, Nebraska, and Wyoming – five states that have not legalized marijuana. 

While the evidence put forth by this data is not meant to be conclusive about the effects of marijuana legalization on road safety, it does provide a degree of insight into the relationship between the two.