After legalization, teen marijuana use drops sharply in Colorado

Teen marijuana use fell sharply in Colorado in the years 2014 and 2015, after the opening of that state's recreational marijuana market, new federal survey data show.

The state-level data from the National Survey on Drug Use and Health showed that 18.35 percent of Coloradans ages 12 to 17 had used marijuana in the past year in 2014 or 2015, down sharply from 20.81 percent in 2013/2014. (In this survey, years are paired for state-level data to provide larger sample sizes). That works out to roughly a 12 percent drop in marijuana use, year-over-year.