It’s no surprise that legalizing a drug correlates with a spike in consumption of said drug, and that’s exactly what happened in Washington and Colorado after marijuana possession was legalized in 2012.

According to numbers released in December by the Substance Abuse and Mental Health Services Administration, the share of Washington residents ages 12 and older who reported monthly pot use jumped from 10.2 percent in 2011-12 to 12.3 percent in 2012-13. In Colorado, the spike was 10.4 percent to 12.7 percent.

Nationally, monthly pot use grew from 7.1 percent to 7.4 percent.

The survey took place in 2013, after Initiative 570 legalized the possession of marijuana in Washington but before the state’s pot retail system was put into place.

Many I-507 opponents cited increased use among teens as an inevitable downfall of legalization, but that hasn’t yet appeared in the data. In Washington, the rise in monthly use among teens ages 12-17 was nearly flat, shifting from 9.5 percent in 2011-12 to 9.8 percent in 2012-13. In contrast, the marijuana use rate among those ages 18-25 jumped from 23.4 percent to 25.6 percent, and the share of smokers in the 26-and-older cohort rose from 8.1 percent to 10.3 percent.

Shoppers visit Bellevue marijuana retailer Green-Theory in October. Photo by Jake Bullinger.

Shoppers visit Bellevue marijuana retailer Green-Theory in October. Photo by Jake Bullinger.

The legalization law included numerous safeguards to prevent use among those younger than 18, including buffer zones around schools and public spaces and funds earmarked for drug awareness education.

Marijuana consumption rates will almost surely rise in 2014 and 2015 on the heels of Washington’s retail system, but teen use might remain low. Identification is necessary to enter marijuana stores, and the current pot-buying demographic, particularly on the Eastside, is an older one.

“Most people I’ve spoken with are folks who haven’t smoked since the mid-’70s,” said Grant Dettmering, a sales associate with Green-Theory in Bellevue. Stores like Green-Theory and Herbal Nation in Bothell have trained their sales staff to cater to an older customer base that “don’t want to meet people in odd places,” Dettmering said. “We’re giving people who aren’t comfortable with the black market or the medical market a place to come and get marijuana.”

The small uptick in teen use (nationally, teen use dropped) could, of course, be exaggerated. Surveys are only as accurate as the answers received, and teens who acquire marijuana from the black market could withhold information about their consumption. And the black market is still a viable choice for cost-conscious pot users — prices in the stores can be triple what street dealers charge.

The state hopes that, as more retailers open and production increases, prices will drop and the black market will eventually be squeezed out.

According to the SAMHSA data, Washington is one of eight states with at least 10 percent of residents using pot monthly. Rhode Island tops the nation with 14.1 percent of residents using marijuana monthly.