In Colorado, the first state in the country to allow legal recreational cannabis sales to adults, youth marijuana use is going down, according to newly released survey results.

Fewer than 13% of Colorado’s high schoolers last year reported using marijuana at least once in the previous 30 days. That is the lowest percentage since at least 2013 — the year before recreational pot shops opened in Colorado.

The percentage of high schoolers who reported ever using marijuana — 26.3% — is 10 percentage points below 2013 levels.

The numbers come from the latest edition of the Healthy Kids Colorado Survey, an every-other-year snapshot of the physical, mental and behavioral health of Colorado’s youth. The survey is a collaboration between the Colorado Department of Public Health and Environment and researchers at the Colorado School of Public Health.

This version of the survey polled more than 120,000 students across the state, making it by far the largest study tracking youth behavior in Colorado. The results have margins of error of around +/- 1 percentage point.

In addition to marijuana use numbers being down, several other metrics are also trending in perhaps counterintuitive directions following Colorado’s legalization of cannabis. For instance, the percent of high school students who say marijuana is easy to get was 14 percentage points lower in 2023 than in 2013.

Meanwhile, perceptions of disapproval of marijuana use are going up. More than 70% of Colorado high school students said they think it is wrong for someone of their same age to use cannabis — 10 percentage points higher than in 2013. More than 89% say they think their parents or guardians would disapprove of them using marijuana.

Differing views over what gets credit

Advocates for cannabis legalization were quick to credit the policy’s impact for the shift.

“Colorado continues to be proof that regulating cannabis works,” Chuck Smith, the board president for Colorado Leads, a cannabis industry group, said in a statement.

Opponents of legalization point out that not all schools participate in the Healthy Kids Colorado Survey. The 2023 survey saw participation from 344 schools, but there were notable gaps in some areas of the state where large numbers of districts or students opted out of the survey. So while the survey is big, it may not be as comprehensive as possible.

The survey also isn’t precise enough to capture all trends around potentially concerning behavior. For instance, after Colorado legalized recreational cannabis use for adults, the percentage of adults reporting daily or near-daily use of marijuana increased.

But the Healthy Kids Colorado Survey doesn’t have a question about daily use. So, while the number of high school students who reported using marijuana in the prior month has gone down, there’s no way of knowing whether those teens who are using marijuana are doing so more or less frequently than in prior years.

In a statement, Rachel O’Bryan, a co-founder of the group One Chance to Grow Up, which is concerned about the commercialization of cannabis, said policies adopted after legalization took effect have had a significant impact in keeping teens from using marijuana. She pointed especially to laws that tightened rules around high-potency cannabis concentrates and that warned youth about the health impacts on developing brains from using marijuana.

“While the 2023 Healthy Kids Colorado Survey results have reassured us that the work of One Chance to Grow Up has benefited Colorado children and their families,” O’Bryan said in her statement, “we see there is much more to do to protect kids from commercial high-concentrate marijuana.”

A nationwide trend

The drop in cannabis use, though, isn’t happening in isolation. Colorado teens are shying away from all kinds of behaviors that health leaders would consider risky.

For instance, fewer teens are binge drinking in Colorado. Vaping is down. And fewer high schoolers are having sex — about 45% of 18 year olds in high school report having ever had sex, the first time that datapoint has come in below 50% since at least 2013.

Meanwhile, the Healthy Kids Colorado Survey found improvements in teen mental health. More high schoolers say their stress level feels manageable most days. Far fewer report persistent feelings of sadness or hopelessness, 26% compared with 40% in the pandemic-era 2021 survey. Fewer teens also reported contemplating or attempting suicide in the prior year. 

The decline in cannabis use among high schoolers in Colorado fits with a similar decline nationally. In 2013, 23.4% of high schoolers nationally reported using marijuana at least once in the previous 30 days. In the most recent federal data available, that percentage is now 15.8%. Those numbers are from 2021, though, so they are not a direct comparison to Colorado’s newest figures.

Given the consistency of these apparent trends, though, one other datapoint especially stands out: Teens themselves seem skeptical that this is actually happening.

When asked whether they believe half or more of the students in their grade level used marijuana, 51% of high schoolers said they did. That’s a significant increase over the 2021 survey.