The latest Gallup poll finds record public support for legalizing marijuana, including a majority of Republicans for the first time in the half a century the organization has been asking the question. According to the poll, which was conducted October 5 to 11, 64 percent of all American adults and 51 percent of Republicans think "the use of marijuana should be made legal," up from 60 percent and 42 percent, respectively, last year.

Overall support for legalization has been rising since the mid-1980s, but the upward trend has accelerated in recent years as more and more states have moved away from prohibition. After rising by 10 points (29 percent) between 2001 and 2009, the percentage of Americans who say pot should be legal rose by 20 points (45 percent) between 2009 and 2017. The shift among Republicans has been even more dramatic, with support rising by nine points (21 percent) in just the last year.

There is still a gap between Democrats and Republicans on this issue, but it is narrowing. In 2010 Democrats were almost twice as likely as Republicans to favor legalization. Last year support was 28 points, or 67 percent, higher among Democrats. This year the difference is 21 points, or 41 percent.

Rising support for legalizing marijuana seems to be a function of growing familiarity with it, which is in turn correlated with age. In another Gallup poll conducted last July, 45 percent of adults admitted trying marijuana, more than 10 times the number in 1969. Direct experience with marijuana was most common among 30-to-49-year-olds, 51 percent of whom said they had tried it, and least common among respondents 65 or older, only 23 percent of whom said they had. Support for legalization is also lowest in the oldest cohort, which is the only age group in which a majority still opposes it.

As the oldest cohort dies off, Republicans as well as Democrats are increasingly likely to say marijuana should be legal. It was already true that most Republicans thought the federal government should not try to stop states from legalizing marijuana. Now it looks like most of them have turned against pot prohibition, further complicating any plans Attorney General Jeff Sessions might have to make a last stand in its defense.

"As public support for ending marijuana prohibition continues to grow, it is crucial that states continue to be given the freedom to serve as laboratories of democracy," says Morgan Fox, director of communications at the Marijuana Policy Project. "We urge the Department of Justice in particular to continue its policy of not interfering in states with well-regulated adult-use and medical marijuana programs while lawmakers catch up to the will of the people."