In 2000, when a Pew Research Center poll found that 30 percent of Americans supported the recreational use of marijuana, broad legalization of the drug seemed unthinkable. In January, that same poll found that 61 percent of Americans supported legalizing the use of pot.

What was once unthinkable is becoming unstoppable. But if legal pot is not properly taxed and regulated, the consequences would be unbearable.

Last month was an extraordinary one for legalization momentum. U.S. Senate Minority Leader Chuck Schumer, once an opponent, said he would introduce federal legislation to decriminalize marijuana and leave regulation to the states. Passage would mean that federal prosecutions and persecutions of users and suppliers, still an issue even in states that have legalized, would no longer be a threat.

Former House Speaker John Boehner, who in 2011 said he was “unalterably opposed” to legalization, announced a change of heart. He has joined the board of Acreage Holdings, a multistate marijuana corporation, and says ending the federal prohibition would allow scientific study of the drug’s benefits, assist veterans who can be helped by its use and stem the opioid epidemic.

President Donald Trump is signaling he won’t let anti-pot Attorney General Jeff Sessions crack down in the nine states where recreational use is legal or the 20 more that allow medical marijuana. And the increasing benefits felt by older Americans suffering from chronic pain, cancer, glaucoma and other illnesses have created an unexpected source of support.

The public’s change of heart is justified by data. The path for states with full legalization has generally been smooth. There have been no huge surges in crime or addiction, and evidence shows opioid use and related deaths decline in states that legalize medical marijuana and drop even more in states that allow recreational use. Tax revenue has flowed in, with marijuana sales generating $250 million for Colorado in 2017. Pointless prosecutions that often disproportionately punished minorities have stopped.

Schumer’s bill and similar ones in the House are not likely to pass yet. Both chambers are controlled by Republicans, and while pro-marijuana sentiment is rising among GOP voters, it’s not yet great enough to force leaders to support legalization. Right now, the most important decisions are being made at the state level, but it’s becoming clear that federal decriminalization also will be necessary to address some needs.

FROM AN EDITORIAL IN NEWSDAY