Marijuana use among teenagers hasn't really changed since legalization
The study surveyed 17,000 high school students in Colorado who self-reported their marijuana use.
In 2015, 21% of teens reported that they had used marijuana at least once in the past 30 days, down from 25% in 2009.
Furthermore, 38% of teenagers reported that they had smoked marijuana at least once in their lifetime, down from 43% in 2009.
"The survey shows marijuana use has not increased since legalization, with four of five high school students continuing to say they don't use marijuana, even occasionally," the Colorado health department said in a press release.
But even with legalization, Colorado's teen use rates are actually consistent with the national average - both are around 21%.
The study also showed that teens whose parents view marijuana use as wrong were four times less likely to smoke marijuana.
Alcohol is still the most used substance among Colorado teens, with 59% reporting that they had drank alcohol in their lifetime. Only 20% of teens, however, reported trying cigarettes.
"Colorado is proving that you do not need to arrest thousands of responsible adult marijuana consumers in order to prevent consumption by teens," Mason Tvert, the director of communications for the Marijuana Policy Project said in a statement. "State and local officials now have more control than ever over who is selling marijuana, and there are strict rules in place to prevent sales to minors. Regulation is working."
Policymakers are closely watching Colorado's example, as a number of states are set to vote on legalizing recreational and medicinal marijuana on November 8.