WASHINGTON - Voters in Alaska, Oregon and Washington, D.C., approved marijuana legalization measures by comfortable margins on Tuesday. The votes signal that Americans are ready to expand upon the legalization experiments already ongoing in Colorado and Washington state, which opened up recreational marijuana markets this year. A medical marijuana amendment also received majority support in Florida, but it fell two percentage points short of the 60 percent supermajority required for passage.

The victories are significant because they come despite a midterm election holding huge structural advantages for Republicans. Support for marijuana reform is concentrated among the young, but 18- to 29-year-olds made up only 13 percent of the 2014 electorate, compared to 19 percent in 2012. "Now that it's been shown that putting marijuana legalization on the ballot can succeed even in midterms, we can expect to see a huge surge of additional states voting to end prohibition during the 2016 presidential election," Tom Angell of the advocacy group Marijuana Majority said in an email.

Alaska's vote made it the first red state to create a fully legal recreational marijuana market. It will eliminate the confusion over Alaska's often contradictory marijuana regulations. Exit polls there show that the measure, which passed 52-48, garnered majority support among every age group except those aged 65 and over. There was, however, a sharp partisan divide, with 74 percent of Democrats supporting the bill compared to only 30 percent of Republicans. A majority (58 percent) of Alaska independents favored the bill.

The partisan breakdown behind Oregon's vote was similar. But national-level exit polls show that marijuana legalization has the potential to draw on a broad, bipartisan base of support: Republicans made up nearly 40 percent of legalization supporters nationwide. This shows that there's broader cross-party agreement on marijuana legalization than on gay marriage, an issue in which Republicans make up only 31 percent of supporters nationally.

"Reform of marijuana and criminal justice policies is no longer just a liberal cause but a conservative and bipartisan one as well," said Ethan Nadelmann of the Drug Policy Alliance in a statement. He also noted that several drug policy reform measures passed the House this congressional term. "The fact that 1/8Speaker 3/8 John Boehner would allow two votes on marijuana to go to the floor and win - that suggests a significant measure of bipartisan support," he added in an interview.

Legalization proponents can now claim sizable momentum as they turn their attention to 2016, with efforts already underway to put legalization on the ballot in California, Massachusetts, Maine, Nevada and Arizona. The Marijuana Policy Project is focusing on legislative efforts in Delaware, Hawaii, Maryland, New Hampshire, Rhode Island and Vermont.

Democratic strategists will likely note that marijuana received overwhelming support in an election where Democratic candidates took a beating at the polls. In Alaska, for instance, incumbent Democratic senator Mark Begich kept his distance from the marijuana initiative, but voters passed it anyway. With Begich poised to lose to his Republican rival, Democrats may need to reconsider this strategy.

"It's possible that the Democratic party will begin to see marijuana legalization as a useful thing to have on the ballot in the same way as minimum wage," Nadelmann said. Preliminary exit polls in Florida suggest the medical marijuana measure there may have boosted turnout among 18-29 year olds, a key Democratic constituency.

While the Florida measure fell just short of the threshold needed to pass, the Brookings Institution's John Hudak says "there's a lot for the legalization movement to hang their hat on" there. "It's a big, diverse, difficult-to-predict state. Coming up a little short in Florida is going to help them craft their message and strategy better for the next go-round in other states." All told, the raft of measures on the ballot this year gives legalization proponents "a gameplan to see what worked, and what didn't," Hudak said.

Legalization opponents, who were vastly outspent this election cycle, are regrouping and considering their next move. "We will redouble our efforts," said Project SAM's Kevin Sabet in a statement. Opponents took some solace in a smattering of local elections in Colorado, where five municipalities voted to ban marijuana businesses. It's also an open question whether the Republican-controlled 114th Congress will show the same enthusiasm for drug and sentencing reform as the 113th.

One area of possible contention will be D.C., where 69 percent of residents voted in favor of legalized marijuana. The D.C. city council must now decide how to implement a legal market, but both the ballot measure and any resulting legislation are subject to approval by Congress. With a nearly 70 percent mandate from D.C. voters, it doesn't seem likely that the next Congress will want to kick things off with a showdown over marijuana reform.

The symbolic importance of legalized marijuana in the nation's capital, home to the Drug Enforcement Administration and the command center of the so-called "war on drugs," is not lost on anyone. But the biggest effects of Tuesday night's votes may be felt internationally. When Washington and Colorado legalized marijuana in 2012, they created political space for other nations to experiment with drug reform.