Roads are more dangerous in states where recreational marijuana is legal. But why, and what can be done?
In 2011, there were no states in which recreational cannabis was legalized. As of April 2025, there are 25, with more imminent. For all the medicinal benefits such changes may have facilitated, the impact of widening cannabis legalization has had some negative effects.
As our analysis reveals, such sweeping drug changes – the recreational legalization of cannabis involves half the country’s states – have already had a far-reaching impact. Cannabis sales have been linked to a 6% rise in car crashes and a 4% rise in fatal crashes, with states such as California, Colorado, Nevada, Oregon, and Washington recording significant fatality hikes.
Ultimately, our findings show that marijuana legalization has made our roads more dangerous. We consider what the data reveals and look at some of the challenges involved.
The Rise of Cannabis Use and Its Correlation with Crashes
As might be expected, as cannabis laws are relaxed, cannabis use is on the rise. By 2019, 18% of individuals aged 12 or over (48.2 million people) reported that they’d used cannabis, up from 11% (30 million) in 2002.
Pre-pandemic, 21% of drivers involved in fatal crashes tested positive for cannabis. During the pandemic, 33% of fatal car crashes were attributed to cannabis use – compared to 29% in which alcohol was the predominant factor.
The car accident data is further complicated if we consider a combination of cannabis and alcohol consumption. Pre-pandemic, 18% of drivers involved in fatal crashes were found to have multiple substances in their system. Post-pandemic, that figure rises to 25%.
States Where Marijuana Is Legal Are More Dangerous for Drivers
As the study data suggests, states in which recreational marijuana is legal have experienced an overall increase in motor vehicle deaths and collision claims. Specifically, there have been substantial cannabis-related increases in crash fatalities in Colorado (16%), Oregon (22%), Alaska (20%), and California (14%).
This data underscores a clear correlation between cannabis use and car accidents. And the data would appear to lay the vast majority of responsibility with those using cannabis recreationally.
States that have legalized recreational cannabis experienced a 4–6% increase in fatal and injury crashes, while those with medical cannabis laws in place saw an 8–11% reduction in traffic fatalities.
Recreational Marijuana’s Negative Effect on Driving
As the data further emphatically establishes, drivers who use marijuana suffer impaired reaction times, judgment, and coordination, increasing their likelihood of being involved in an accident. And, according to our analysis, 85% of cannabis users drive the same day they use the drug, 53% within an hour of using it.
Such casually dangerous behaviour can in part be attributed to the misapprehension that law enforcement won’t notice. 29.2% of cannabis users doubt police will be able to tell they’ve been using cannabis: significantly more than the 26% who believe police will be able to notice.
Yet there is clear recognition that to drive whilst under the influence of cannabis is dangerous and would draw disapproval from others. 70% of marijuana users feel that it would be ‘highly dangerous’ to drive within an hour using the drug, while 93% say their friends and family would disapprove of post-use driving.
Our analysis also reveals widely different levels of access to cannabis across all states. Besides the 25 states in which recreational cannabis is legal (although in Washington D.C., while cannabis possession is legal, sales of the drug are prohibited) 38 states variably permit the medicinal use of the drug.
Possession limits add further distinctions: for example, Alaska limits recreational possession to 1 ounce, yet permits 2.5 ounces of medicinal marijuana possession every 14 days. California allows 8 ounces for medical use, whereas Georgia law stipulates an allowance of up to 20 fluid ounces of cannabis oil.
Delaware allows the application of cannabis oil for minors; Idaho and Nebraska are just two examples where neither recreational or medical possession or purchase are allowed. From a road safety standpoint, increased access generally equals more accidents.
More Vigilance or Restrictions May be Needed to Improve Safety
Cannabis laws have been significantly relaxed over the past few years (with the possibility of more relaxation in currently prohibitive states). Since the data tells us that this has led to more road accidents, it would be reasonable to suggest that this trend will increase in line with wider access to cannabis.
Clearly, stricter allowances (and/or public awareness of dangers) are needed in states that allow the recreational sale of cannabis, and more vigilance may be needed regarding the use of vehicles by all cannabis users.
As our analysis has shown, drivers understand the dangers of driving while under the influence of marijuana, yet still do so in significant numbers.
Ultimately, The Texas Law Dog understands the problems around variable marijuana regulations, and their distinct impact on our roads. Without any changes or interventions, car crash anomalies in permissive states will persist.
But with car crash fatalities on the rise, focusing on cannabis and its involvement in car accidents is one way to bring the numbers down.
