A national Pew Research Center poll released Thursday shows the majority of Americans support pot legalization 52 percent to 45 percent, with 72 percent who say that the cost of federal law enforcement efforts are not worth it.

The results mark the first time in more than four decades of Pew's polling that a majority has taken that position. As recently as a decade ago, only about one-third of American adults backed making marijuana legal. Support for legalizing pot is up 11 points since 2010, the most dramatic change since the late 1960s, according to pollsters. A Gallup survey conducted in 1969 found only 12 percent favored legalizing marijuana use.

The latest poll also found the percentage of people who say they have used marijuana in the past year (roughly 1 in 10) or at any point in their lives (roughly half) is virtually identical in states that have legalized some marijuana use and those that have not, suggesting that more liberal laws have simply made usage more visible, not increased it, as some have feared.

The numbers are driven in part by an apparent shift in how baby boomers feel about the drug of their youth. The poll found most Americans don't see marijuana as a "gateway" to more dangerous drugs anymore, and the majority no longer see use as immoral. Half of Americans said use was immoral as recently as 2006 -- now that number has dropped to a third, while half say that marijuana usage is "not a moral issue."

"It's time for politicians to catch up to the voters on this issue," said Marijuana Majority spokesman Tom Angell. "Not too long ago, it was widely accepted in political circles that elected officials who wanted to get reelected needed to act 'tough' on drugs and go out of their way to support the continued criminalization of marijuana. The opposite is quickly becoming true. A majority of Americans support legalizing marijuana, and you're going to start seeing more politicians running toward our movement instead of away from it, just as we've seen happen with marriage equality recently."

The poll's most marked divisions are by age, with younger Americans being significantly more likely to support legalization than older Americans.

Parenthood also appears to be a significant indicator, as the Los Angeles Times notes in its report . Among respondents between the ages of 30 and 49, parents are much less likely to support legalization than non-parents. Parents with school-aged children at home were closely divided on the issue, while those without children at home support pot legalization by 62 percent.

The Pew poll was conducted March 13 to March 17 by telephone among 1,501 American adults. The margin of error is 2.9 percentage points.