Nearly two years after the nation's first recreational marijuana shop opened in Colorado, American support for legal pot has tied an all-time high and is likely to increase, according to new numbers released today by Gallup. Fifty eight percent of Americans say that the use of marijuana should be legal, a seven-point year-over-year increase.

The poll finds steady increases in support of legalization across all age cohorts. For instance, in 1969 only 20 percent of those born between 1935 and 1950 supported making marijuana legal. Today, 40 percent of that age group — who are now 65 or older — support legal pot.

Similarly, in 1985 only 32 percent of boomers born between 1951 and 1965 supported legal marijuana. Today, 58 percent of them do. Support is highest among young adults born between 1981 and 1997, 71 percent of whom support legalization, according to Gallup.

"Americans' support for legalizing marijuana is the highest Gallup has measured to date, at 58%," the survey concludes. "Given the patterns of support by age, that percentage should continue to grow in the future."

This comes after Colorado and Washington state opened their recreational marijuana markets in 2014, and voters in the District of Columbia, Alaska and Oregon approved legalization measures last fall. With Ohio voters considering legalization in just a few weeks and a number of other states planning to vote on legalization next year, it seems that marijuana reform proponents are enjoying a strong tailwind in support.

"These days it’s not especially exciting to see yet another poll showing majority support for legalizing marijuana, but 58 percent is very strong share of the American people calling for change, and elected officials should listen," said Tom Angell of the pro-legalization group Marijuana Majority. "We’re seeing an increasing number of national politicians saying that it’s time to at least let states implement their own laws without federal interference. And we’re also seeing a growing number candidates endorsing legalization outright, which shows how mainstream this issue is now."

Indeed, at the recent Democratic presidential candidate debate Sen. Bernie Sanders indicated he would support a marijuana legalization measure to be put before Nevada voters next fall. Hillary Clinton recently reaffirmed her support for letting states chart their own course on marijuana reform. And just across our border to the North, the incoming Canadian prime minister Justin Trudeau has promised he would start work on legalizing marijuana in that country "right away."

Anti-legalization groups, including government agencies like the Drug Enforcement Administration, have tried to convince the public that legalization has been a mistake and a failure. They have argued that looser laws will lead to more marijuana use among children and teens, and a rise in marijuana-related crime and car accidents. Some caution that individual poll numbers should be taken with a grain of salt.

"The Gallup numbers have varied wildly in the past few years, so I think we will have to see what the next few years hold," said Kevin Sabet of the anti-legalization group Project SAM. "There's no doubt that a massive new industry resembling big tobacco of yesteryear has spent tens of millions of dollars on messaging."

But efforts to sway public opinion against legalization have occasionally backfired. After dire warnings about the dangers of "marijuana candy" showing up in kids' Halloween baskets last year, Colorado authorities admitted that they uncovered zero instances of Halloween-related pot poisonings. Another article about pot candy published by anti-drug group DARE turned out to be a piece of satire.

Meanwhile, life in Colorado and Washington since legalization has gone on as usual. Crime is down and the economy is up. Cops are spending far less time and resources on low-level marijuana offenses. Tax coffers are overflowing.

In short, the public seems to be coming around to the notion that smart marijuana legalization can be a win-win situation.

This post has been updated with a statement from Kevin Sabet of Project SAM, an anti-legalization group.