Among 683,000 MVC drivers at US trauma centers, cannabis-positive results rose from 10.2% to 14.6% between 2017 and 2020, with the sharpest increase among adolescents.
Traffic safety researchers, drug policy analysts, public health officials, emergency medicine professionals
43% increase in cannabis-positive MVC drivers over 4 years
What the researchers found
Analysis of 683,184 motor vehicle crash drivers at US trauma centers found that 28.8% tested positive for drugs or alcohol, with 36.3% of those testing positive for multiple substances. Marijuana was the second most common substance (41.6% of positive tests, after alcohol at 47.1%). Cannabis-related MVCs increased significantly from 10.2% in 2017 to 14.6% in 2020 (P<0.001), with the most prominent rise among adolescents.
Why it matters
This is one of the largest analyses of substance-impaired driving in the US, showing that cannabis-related crashes are rising faster than any other substance category, particularly among adolescents. The trend accelerated even during a period of expanding legalization.
The numbers in context
n=683,184 MVC drivers; 28.8% positive for drugs/alcohol; marijuana found in 41.6% of positive tests; cannabis-positive MVCs rose from 10.2% (2017) to 14.6% (2020), P<0.001; 69% male; median age 43
How the study worked
Retrospective analysis of the American College of Surgeons-Trauma Quality Improvement Program database over 4 years (2017-2020). Included all patients presenting after an MVC as a driver. Trend analysis performed for positive blood or urine toxicology results across substance categories.
What this study cannot tell us
Positive drug screens do not prove impairment at the time of the crash; THC can be detected days after use. Cannot determine causation between cannabis use and crash occurrence. Database covers trauma center admissions only, excluding less severe crashes and fatalities.
How to read the evidence
Very large national trauma database with clear trend data and statistical significance provides strong epidemiological evidence, though inability to confirm impairment at time of crash is a limitation.
When this study was published
2025 publication analyzing 2017-2020 trauma registry data
The bigger picture
As cannabis legalization expands across the US, the parallel rise in cannabis-positive crash drivers raises questions about whether current DUI prevention policies adequately address drugged driving. The adolescent trend is particularly concerning given that no state has legalized recreational use for minors.
Questions still open
- Are rising cannabis-positive crash rates driven by increased use, increased testing, or both? Do states with legal recreational cannabis show different trends than states without?
Common questions
Does a positive marijuana test mean the driver was impaired?
Which age group showed the biggest increase?
Read the original research
The Alarming Surge of Driving Under the Influence-Related Motor Vehicle Crashes.
The Journal of surgical research, 314, 146-152
Citation
Al Ma'ani, Mohammad; Castillo Diaz, Francisco; Hejazi, Omar; Khurshid, Muhammad Haris; Kunac, Anastasia; Stewart, Collin; Colosimo, Christina; Nelson, Adam; Magnotti, Louis J; Joseph, Bellal. (2025). The Alarming Surge of Driving Under the Influence-Related Motor Vehicle Crashes.. The Journal of surgical research, 314, 146-152. https://doi.org/10.1016/j.jss.2025.07.020