The devil’s weed. Photo: Matt McClain/The Washington Post via Getty Images

The American people are smoking a lot more weed these days. According to a Gallup poll released Monday, 13 percent of the country “currently smokes marijuana.” Just three years ago, that figure was 7 percent.

In total, more than 33 million Americans are now active cannabis users. To put that in perspective, roughly 40 million Americans smoke cigarettes. With the latter population steadily decreasing, it may not be long before there are more pot tokers than tobacco smokers in this shining city on a hill.

As Vox’s German Lopez notes, part of this increase could be smoke and mirrors: It’s possible that some longtime marijuana users are just coming out of the (hot-boxed) closet now that our culture puts less stigma on their habit. But it’s also likely that the legalization of recreational weed in four U.S. states has generated a wave of new users — both by providing over-the-counter access to the drug and by eroding that aforementioned stigma.

When weighing the costs and benefits of marijuana legalization, most public-health experts would put “a significant increase in cannabis use” in the former column. While marijuana is one of the safest mind-altering substances a human can use, it still has its drawbacks. As Lopez notes, some studies suggest that a minority of weed smokers suffer negative outcomes, ranging from psychological dependence, car accidents, or temporary psychosis.

Nonetheless, the case for marijuana legalization remains strong due to the tremendous costs of prohibition. Those costs can be measured in the hundreds of thousands of Americans who are arrested for possession of the drug each year — torn from their communities for indulging in a substance safer than alcohol — as well as in the profits that accrue to criminal cartels when the primary market for pot is an illegal one.

Plus, there may actually be some benefits to the increased prevalence of marijuana use. If a significant number of new weed users are substituting cannabis for opioid painkillers or alcohol, then their new habits might represent a net win for public health: Some studies have linked the availability of legal marijuana with decreases in opiate overdoses and traffic fatalities.