Marijuana prohibition in the United States could be dealt a major blow in November, with five states voting on legalizing the adult recreational use of cannabis.

If current polling trends are any indication, voters in all five states — Arizona, California, Massachusetts, Maine and Nevada — are likely to approve their respective legalization measures. that would double the number of jurisdictions in the United States that have ended prohibition.

Voters in Alaska, Colorado, Oregon, and Washington have all approved measures to legalize, tax and regulate adult cannabis sales, while voters in the District of Columbia have passed a law that allows adults to grow and possess (but not purchase) marijuana.

But of course, none of those states can match the sheer numbers in California, the largest state in the country.

Consider this: The combined population of all areas of the United States where prohibition has already ended totals just 17.5 million. That’s not even half the population of California.

Simply put, if California’s Proposition 64 alone is approved by voters—in the unlikely event that legalization suffers a defeat in the other four states—the number of people living in a state with legal weed will more than double overnight.

Arizona is the 15th largest state in the country, with 6.6 million residents. This is a true red state, with a highly conservative population—but one with a libertarian bent, and where medical marijuana was passed by voters in 2010. Originally seen as a long shot, Arizona’s marijuana legalization measure, Proposition 205, is currently bringing in 50 percent support, with only 40 percent opposed, according to a highly respected Arizona Republic/Morrison/Cronkite News poll released in early September. Fifty percent support is a great position for legalization in a state as conservative as Arizona.

Still, with 10 percent of voters polled still undecided, the battle to free the herb in Arizona could heat up as the election draws closer. (An April 2016 poll conducted by pot-prohibitionists Arizonans for Responsible Drug Policy, found only 43% support for legalization, with 49% opposed.)

Now let’s look at California, a state which defeated a marijuana legalization proposal in 2010. The latest poll, released this week, has the widely supported Proposition 64 commanding 60 percent support from voters, with only 31 percent opposed. Two other recent polls have Prop 64 in the lead, with a conservative Survey USA poll showing 52 percent in favor of the measure, and a Los Angeles Times poll reporting 58 percent support. An August poll, which did not ask respondents about any specific ballot questions, found that 64 percent of voters believe “marijuana should be legal for adults to purchase and use recreationally, with government regulations similar to the regulation of alcohol.”

In the face of this, even traditional bastions of conservative thought in the state have flipped. The Los Angeles Times, for almost a century and a half the dominant GOP voice in the state and a perennial anti-pot voice, endorsed Prop 64.

Whatever happens elsewhere, what seems to be a certain win in California would certainly be a major tipping point for marijuana legalization nationwide. Not only would the entire Pacific coast be comprised of legalized states, but with a population of over 38 million, California would single-handedly deliver reform to 12 percent of the United States population.

Across the country in the Northeast, we have Massachusetts going for the marijuana hat trick. Sixty-five percent of voters approved decriminalizing up to an ounce of marijuana in 2008, followed by 63 percent of voters approving medical marijuana in 2012. This year, Bay State voters will decide on legalization on Question 4 on the ballot. A poll released last week has support of the proposal at 50 percent, with 45 percent opposed.

That’s significant, because the Massachusetts law is as broad as we’ve seen. The question presented to Massachusetts voters includes allowing cannabis cafes, similar to bars, where marijuana will be allowed to be consumed on-site. People would be allowed to possess up to ten ounces at home (one ounce in public), and retail sales are subject to a modest ten percent tax statewide (a 3.75 percent excise tax, in addition to the state’s 6.25 percent sales tax). Local cities and towns could add an additional two percent tax, meaning that cannabis consumers will be paying at most a 12 percent tax.

While 50 percent support is great news for legalization supporters—a simple majority, even by one vote, is all that is needed in Massachusetts to pass the measure—you always have to remember the margin of error, which in this case would mean this race remains close. Voter support in Massachusetts traditionally has been higher than polls suggest, at least when it comes to marijuana reform. In 2012, for example, polling had support for medical marijuana at 58 percent, significantly less than the 63 percent approval for the ballot measure eventually garnered.

But it seems as if support for legalizing marijuana continues to grow in Massachusetts, with another poll, released Wednesday, finding 53 percent of Bay State voters in favor of Question 4, with only 40 percent opposed and 7 percent remaining undecided.

Once a part of Massachusetts, the nearby New England state of Maine will also be voting on marijuana legalization in November as ballot Question 1. On Monday, the Portland Press Herald released a poll indicating 53 percent support of the measure statewide, with only 38 percent opposed—more good news for the legalization movement.

Finally, voters in Nevada will be presented with Question 2. A KTNV/Rasmussen Reports poll released last week found 53 percent of likely voters support the measure, with only 39 percent opposed. Support has grown since a similar poll in July, also conducted by KTNV/Rasmussen, found 50 percent support for legalization, with 41 percent opposed. Rasmussen polls tend to lean Republican, which could indicate even higher support for legalization in Nevada, a state that already regulates gambling and prostitution.

A clean sweep of all five measures passing would bring the total population living in areas where marijuana is legal for adults to possess and consume to over 73 million, which is roughly 23% of the total population of the United States.

What’s more, if all five measures pass, it could prove to be a catalyst for other states wanting to join the cannabis legalization bandwagon to follow suit, as lawmakers scramble to have their states join the “green rush” before it becomes less profitable to do so.

The Holy Grail for marijuana reform advocates, of course, would be an actual state legislature passing a law in the upcoming legislative session to legalize marijuana for adults. With only 24 states in the nation allowing the referendum process, more than half the country will be reliant upon their state lawmakers to free the herb. So far, no legislative body has done that, although one state came close last year.

Last year, lawmakers in Vermont came the closest when the state Senate made history by approving a bill 17-12 to legalize marijuana for adults. Despite support from Vermont Governor Peter Shumlin, the bill was killed in the House in early May. If Maine and Massachusetts both approve their measures this year, look to lawmakers in both Vermont and Rhode Island to seriously consider legalizing marijuana for adults next year.

With next year’s upcoming legislative session is still several months away, all eyes will be turning to the five states voting on legalization in November — especially California. If you are a resident of any of these states, please be sure to register to vote so you can help end marijuana prohibition in November — not just in your state, but around the country as well.