Road Safety Isn't Negatively Impacted By Cannabis Legalization, Data Shows: Booze Is A Different Story

This article was originally published on MG Magazine and appears here with permission.

Cannabis legalization does not lead to increased fatalities on the road, according to a recent Quartz study that examined the number of deaths per one million vehicle miles in states with and without comprehensive cannabis legalization compared with the national average.

Using data sourced from the National Safety Council, researchers collected vehicle death rates and aggregated fatality rates in four states that legalized cannabis for adult use in 2016—California, Maine, Massachusetts, and Nevada—and compared them with the national average.

Researchers also compiled the same crash data from five states without recreational cannabis laws in place—Idaho, Indiana, Kansas, Nebraska, and Wyoming—to paint a nuanced picture of legalization.

Graph: Quartz

Key findings:

• Traffic fatalities increased across the country by 6.2 percent from 2016 to 2021.
• Traffic fatalities increased in California, Maine, Massachusetts, and Nevada by 6 percent from 2016 to 2021, slightly below the national average.
• Alcohol played a factor in nearly one-third of all automobile-related fatalities from 2016 to 2021.

According to the study’s authors, 2020 and 2021 were anomalies across the country in many regards, including motor vehicle incidents.

“After decades of declining accident rates in the U.S., traffic fatalities picked up in 2020 and stayed high through 2021,” the report states. “The U.S. as a whole saw traffic fatality rates spike 18.9 percent from 2019 to 2021.”

Graph: Quartz

If these two outlier years are excluded from the data set, traffic fatalities differ significantly between the four states that legalized cannabis in 2016 and the five that did not.

The national traffic fatality rate dropped by 10.6 percent between 2016 and 2019 and fell 11.6 percent in the four states that legalized cannabis in 2016. During the same three-year period, the average traffic fatality rate increased by 1.7 percent in the five states without recreational cannabis laws. In Massachusetts, which saw the largest change, traffic fatalities dropped by 28.6 percent during the three years following cannabis legalization.

The Quartz study’s authors also cite data from a December 2022 Casualty Actuarial Society (CAS) report that examined property and casualty insurance using U.S. and Canadian accident data from 2016 to 2019 to examine the effects of legalization on traffic safety.

“The tests for the decriminalization effect on fatalities failed to detect a statistically significant change,” the CAS report states. “The analysis showed no statistically significant changes in the average cost per claim and claim frequency after marijuana legalization in Canada. The quarterly data available for Quebec led to similar findings.”

While the Quartz analysis does not provide clear reasons for the change in traffic fatality rates, the CAS report does speak to the risk associated with cannabis impairment behind the wheel.

“The literature review shows that while marijuana impairment affects driving behavior, the behavior is not always riskier; for example, slower speeds and longer following distances of impaired drivers have been reported,” the report states. “The observational studies of road accidents report mixed results, most often not detecting significant effects, particularly in the long term.”

Forbes Advisors published its findings on the most dangerous states for drunk driving in 2023, citing Montana as the worst state for drunk driving with 8.57 drunk drivers involved in fatal crashes for every 100,000 licensed drivers. The top five most dangerous states—Montana, South Dakota, Texas, Wyoming, and North Dakota—have not passed adult-use cannabis laws.