As cannabis legalization continues to sweep states across the country, we’re collectively able to examine trends regarding the potential positive and negative effects of a more widespread, adult-use cannabis market. One notion around cannabis legalization continuously points to the potential for more traffic accidents and increased danger on the road, but one new study, specifically looking at cannabis legalization and truck driving, suggests the opposite could be true.
The study, humorously titled “Marijuana Legalization and Truck Safety: Does the Pineapple Express Damage More Pineapples?” has researchers from the University of Tennessee, University of Arkansas, and Iowa State University honing in on America’s $800 billion truck driving industry.
Using a state-level panel of heavy truck crash statistics from 2005 to 2019, and a difference-indifference estimation strategy, the researchers tested whether legalization of cannabis has affected the crash rate of heavy trucks. The results show that legalization, in fact, does not increase average crash rates in the states examined.
On the contrary, the research found that recreational cannabis legalization actually reduced the amount of heavy truck accidents by 11%. Specifically, six of the eight states examined, saw a decrease in truck accidents and two saw increases. Vermont and Washington saw the most profound decreases, at -21.5% and -20.1%, respectively, followed by Colorado and Massachusetts, at -18.3% and -18% respectively, and finally Oregon and California, at -3.7% and -3.2%, respectively. The two states reporting increases were Maine at 4.18% and Nevada at 25.6%.
It’s important to note that this is a preprint, meaning that the study has yet to undergo peer review.
Researchers didn’t offer a solid explanation around the reduction in crashes following cannabis legalization, though they offered a couple of theories:
People who might typically drink alcohol could have switched to cannabis. Though it’s still against the law to drive under the influence of cannabis, research suggests that driving high is far less likely to cause a fatal accident than driving under the influence of alcohol. Of course, the safest route is to get behind the wheel fully sober.
They also cite that cannabis is generally consumed at home, rather than at a bar or a restaurant, so even if a trucker partakes, they probably aren’t able to easily access or consume cannabis on the job.
The researchers also wanted to more closely examine the increase in crashes in Nevada by comparing the state to Vermont, which saw the largest decrease by state. They found that Vermont has far less tourism than Nevada, meaning that there are more people traveling who are unfamiliar with the state’s roadways in Nevada. Travelers in Nevada are also more likely to use cannabis outside of the home—like those visiting Las Vegas, for example—indicating a higher likelihood of those folks getting behind the wheel after using cannabis.
Because Vermont is also more densely populated than Nevada, longer stretches of road in the latter state offer more opportunity for crashes.
Some of the findings also contract other recent studies on legal cannabis and driving. One 2021 study from Boston University found that fatal car crashes involving alcohol haven’t decreased over the past two decades, though cannabis-involved fatal accidents doubled, according to the study. Others have suggested that cannabis may increase the overall rates of accidents without necessarily increasing the likelihood of fatal car accidents.
The trucking industry has also faced a number of changes in the wake of cannabis legalization. In January 2020, the Federal Motor Carrier Safety Administration launched its drug and alcohol clearinghouse. It lists all commercial drivers who have failed a drug or alcohol test, though drivers are able to clear their names by following a return-to-duty process.
The clearinghouse is aimed to ensure truck drivers violating drug and alcohol rules aren’t able to quickly secure another trucking job without amending their past behavior and ultimately aims to increase truck safety on the road.
While it’s not fully clear yet how much these aims have increased safety for truckers on the road and other drivers, it has removed a number of drivers. Between January 2020 and April 2022, around 124,000 drivers were removed from their roles as commercial truck drivers because of failed drug tests, and around 31,000 have completed the return-to-duty procedure to return to the road.
Though, the majority of the violations don’t involve drugs like opioids, amphetamines, methamphetamine or cocaine but, you guessed it, cannabis. More than 74,000 truckers who tested positive for cannabis have been removed from commercial truck driving since January 2020.