Medical marijuana is now allowed in 18 states plus the District of Columbia. In November, voters in Colorado and Washington took the movement further, endorsing the sale of marijuana without a prescription for recreational purposes. Both states are establishing regulatory regimens for pot similar to alcohol.
A poll released last month by the Pew Research Center found for the first time a majority of Americans now favor full legalization of marijuana. Fifty-two percent favor decriminalization, with 45 percent opposed.
The level of support is a landmark shift from 40 years ago when just 12 percent backed legalized pot, according to Gallup.
In light of the trend, President Obama told ABC News' Barbara Walters in December that he's re-thinking federal prosecution of some marijuana users.
"It does not make sense, from a prioritization point of view, for us to focus on recreational drug users in a state that has already said that under state laws that's legal," Obama said.
"We've got bigger fish to fry," he added.
The big question now for pro-pot states: Will the Justice Department spoil plans for dozens of new dispensaries, and a potential bonanza of millions in taxes and fees?
The Department, which is reviewing the new Colorado and Washington marijuana laws, has yet to formally decide whether or not they will be challenged in court.
Meanwhile, lawmakers from those states have re-invigorated legislative efforts to repeal or weaken the federal ban on pot. So far this year, seven bills dealing with marijuana have been introduced in the U.S. House, including one that would entirely decriminalize the drug.
All of the bills face an uphill climb, which means for now at least, the new D.C. dispensaries will remain at odds with the law.