HUH: States that legalized marijuana saw a drop in traffic deaths.

“Instead of seeing an increase in fatalities, we saw a reduction, which was totally unexpected,” said Julian Santaella-Tenorio, the study’s lead author and a doctoral student at Columbia University’s Mailman School of Public Health in New York City.

Since 1996, 28 states have legalized marijuana for medical use.

Deaths dropped 11 percent on average in states that legalized medical marijuana, researchers discovered after analyzing 1.2 million traffic fatalities nationwide from 1985 through 2014.

The decrease in traffic fatalities was particularly striking – 12 percent – in 25- to 44-year-olds, an age group with a large percentage of registered medical marijuana users, the authors report in the American Journal of Public Health.

Though Santaella-Tenorio was surprised by the drop in traffic deaths, the results mirror the findings of another study of data from 19 states published in 2013 in The Journal of Law and Economics. It showed an 8 to 11 percent decrease in traffic fatalities during the first full year after legalization of medical marijuana.

Correlation is not causation, of course, and the story also notes that after an big initial drop, fatalities in some states began to rise again. But concerns about stoned drivers making the roads radically more dangerous haven’t materialized, which ought to (but probably won’t) put a stop to some of the Reefer Madness-level panicmongering over legalization.