California, which legalized marijuana for medicinal purposes 20 years ago, is days away from legalizing the plant for recreational use, according to two new surveys.

Fifty-seven percent of likely voters support Proposition 64 ― a measure to legalize the possession, cultivation, use and sale of marijuana for adults 21 and over ― suggests a survey released Friday by Field Poll and the Institute of Governmental Studies at the University of California, Berkeley. That’s similar to the 58 percent support that the University of Southern California’s Dornslife College and the Los Angeles Times found in a poll released earlier this week.

The Golden State is a huge prize for the marijuana legalization movement, because its 40 million residents make it the most populous state in the nation and it has the sixth-largest economy in the world. Pot policy reformers say it would advance their cause considerably if the state adopted legal weed.

California became the first state to establish a medical marijuana program in 1996; since then, about two dozen states have followed suit. In 2010, it had the opportunity to make history again by becoming the first state to legalize recreational marijuana, but voters ultimately rejected that ballot measure. Two years later, Colorado led the way instead, becoming the first state in the U.S. and the first government in the world to establish a regulated marijuana marketplace.

Four states, along with Washington, D.C., have now legalized recreational marijuana (although D.C. continues to ban sales, unlike the state programs).

“In addition to California’s population size and enormous economic and cultural significance, legalizing marijuana there will be hugely politically impactful,” Tom Angell, chairman of drug reform advocacy group Marijuana Majority, told The Huffington Post.

Nov. 8 is the most important day in the history of the marijuana legalization movement. The stakes couldn’t be higher. Tom Angell, chairman of Marijuana Majority

A legal and regulated marijuana marketplace in California would further normalize the sale and use of marijuana, bringing the drug in line with more mainstream substances like alcohol or tobacco. The federal government continues to ban cannabis, classifying it in Schedule I as one of the “most dangerous” drugs, alongside heroin and LSD.

Despite that classification, marijuana is the most commonly used illicit substance in the United States. About 20 million people reported having used the substance in a one-month period, the Centers for Disease Control and Prevention said in 2013. And last year, about 47 percent of U.S. adults said they had used marijuana during their lifetime. Attitudes toward the plant have shifted dramatically in recent years, with support for legalization reaching a high point nationwide last month.

Election Day holds enormous promise for the marijuana movement, with voters nationwide set to consider more ballot measures on weed than ever before.

Four other states ― Maine, Massachusetts, Arizona and Nevada ― will also decide on legalizing recreational marijuana. Medical marijuana legalization initiatives will appear on the ballot in Arkansas, Montana, North Dakota and Florida.

“This is a tremendous year for marijuana,” said John Hudak, a senior fellow at the Brookings Institution who writes extensively on marijuana policy. “In terms of the number of states ― it can double overnight. In terms of the number of people who get added to the rolls of prospective marijuana customers ― it explodes. Some big wins puts some big wind in their sails moving forward.”

If voters approve all legalization measures, almost one-quarter of the U.S. population would live in states with access to some form of legal marijuana.

“An industry that grows is better financed, is better capitalized ― and also has more and better lobbyists,” Hudak said.

And if a significant portion of the marijuana measures pass, especially those in the larger states like California and Florida, the political clout of the marijuana industry could see a huge boost.

“Nov. 8 is the most important day in the history of the marijuana legalization movement,” Angell said. “The stakes couldn’t be higher. Big wins will dramatically accelerate our push to finally end federal marijuana prohibition, perhaps as soon as 2017. But on the other hand, huge losses could interrupt the momentum we’ve been building for the last several years.”

Mason Tvert, director of communications for Marijuana Policy Project, which is playing a leading role in several of Tuesday’s measures, said the ballot initiatives are big steps forward for the marijuana policy reform movement ― even if voters strike them down.

“They have led to an invaluable public dialogue about marijuana, the harms caused by its prohibition, and the benefits of adopting a more sensible approach,” Tvert said. “The debate is steadily shifting from whether marijuana should be ‘legalized’ to how it can best be regulated and taxed for medical and adult use.”