By Adam O'Neal - October 22, 2013

For the first time, “a clear majority” of Americans -- 58 percent -- support legalizing marijuana for recreational use, according to a new Gallup poll. Thirty-nine percent disagree; only 3 percent of respondents were unsure.

The recent surge in support has been primarily fueled by shifting attitudes among independent voters, 62 percent of whom favor legalization, up from 50 percent a year ago.

Partisans’ opinions, which have largely remained fixed over the past year, widely diverge. Only 35 percent of Republicans agree with legalizing marijuana, as opposed to 65 percent of Democrats.

Although younger Americans are still more likely to back the change, previous disparities between generations are disappearing. Only Americans aged 65 and older oppose legalization as a group, while every other age category supports it. Millennials are most enthusiastic, with more than two-thirds in favor.

The poll is a milestone for proponents of changes in marijuana laws. In 1969, when Gallup first posed the same question, only 12 percent of respondents were supportive; 84 percent were opposed, and the numbers remained similarly high into the 1990s. Opposition began to decline toward the end of the millennium and has since rapidly shrunk. A 2011 Gallup poll showed a small plurality of Americans supporting legalization, though that number fell within the poll’s margin of error.

“Whatever the reasons for Americans' greater acceptance of marijuana, it is likely that this momentum will spur further legalization efforts across the United States,” the Gallup report concluded.

Recreational use of marijuana is now legal in Colorado and Washington state (the Obama administration said this summer that it would not challenge either state’s new law). Twenty states and the District of Columbia have legalized marijuana for medical use.

Thirty-eight percent of Americans admit to having tried the drug. Since the mid-1980s, Gallup polls have shown that roughly one-third of the public has acknowledged doing so.

A Pew Research poll earlier this year found a smaller majority supporting legalization.

The nationwide Gallup poll, conducted Oct. 3-6, surveyed 1,028 adults and has a margin of error of plus or minor four percentage points.