A potential sea change in marijuana legislation is coming, with ballot measures in several states giving voters the opportunity to make it legal for adults.

Arizona, California, Maine, Massachusetts, and Nevada will vote on legalizing recreational marijuana, while Arkansas, Florida, Montana, and North Dakota are considering medical marijuana initiatives.

The marijuana industry could quadruple in size after the 2016 elections, according to a new study released Wednesday.

The Los Angeles-based cannabis firm MedMen projects legal pot sales in the U.S. could increase by $20.5 billion per year after voters in nine states weigh ballot measures that would legalize recreational marijuana.

"The potential of this industry is undeniable," MedMen CEO Adam Bierman said. "The question is how we make sure it is done in a safe, responsible and controlled manner."

The recreational use of marijuana has already been legalized in Colorado, Washington state, Oregon, Alaska, and Washington, D.C., and another 21 states permit medical marijuana.

With pot on the ballot in nine states, the big winner in next Tuesday's election could be America's legal cannabis industry. By 2020, legal market sales are expected to surpass $22 billion. And for states struggling with budget shortfalls, that extra revenue would be clearly welcome. 

Voters in five states — Arizona, California, Maine, Massachusetts and Nevada — will decide whether to legalize recreational marijuana for adults. Medical marijuana is on the ballot in Arkansas, Florida, Montana, and North Dakota. 

Supporters believe the marijuana measures will pass in California and Florida, and possibly several other states, because America's attitude about pot has changed significantly in the last few years. 

Nearly 60 million Americans may wake up Nov. 9 to find voters in their states have abolished long-standing marijuana prohibitions, a three-fold expansion for legal cannabis across the country.

Another 24 million Americans could find themselves in states with newly legal medical marijuana use, a smaller but still significant expansion of legalized pot around the United States. Already, half of the states permit some form of medical marijuana use, and more than half of all Americans live in a state that has approved medical marijuana.

The movement to legalize marijuana, the country’s most popular illicit drug, will take a giant leap on Election Day if California and four other states vote to allow recreational cannabis, as polls suggest they may.    – “Election May Be a Turning Point for Legal Marijuana,” The New York Times, Oct 24, 2016

Even by the usual standards of politics, this election’s campaign against marijuana legalization has made strange bedfellows. The largest donors to the various anti-weed political groups around the country include a billionaire casino tycoon, a woman who believes in reefer madness, a drug-crusading former U.S. ambassador, cops, prison guards, booze merchants, and a pharma company that sells the powerful painkiller fentanyl.

To the red-and-blue map of American politics, it may be time to add green. The movement to legalize marijuana, the country’s most popular illicit drug, will take a giant leap on Election Day if California and four other states vote to allow recreational cannabis, as polls suggest they may.

The map of where pot is legal could include the entire West Coast and a block of states reaching from the Pacific to Colorado, raising a stronger challenge to the federal government’s ban on the drug.

In addition to California, Massachusetts and Maine both have legalization initiatives on the ballot next month that seem likely to pass. Arizona and Nevada are also voting on recreational marijuana, with polls showing Nevada voters evenly split.

Elections aside, the marijuana industry has had an incredible run over the past two decades.

Prior to the 1996 approval of a compassionate use medical cannabis law in California, marijuana was illegal in all aspects (medical and recreational), and public support for nationwide legalization stood at just 25% per Gallup. Fast-forward to today and 25 states have legalized medical cannabis, with four states, as well as Washington D.C., legalizing the purchase of recreational marijuana for adults ages 21 and up. It's worth noting that the two most recent states to legalize medical marijuana -- Pennsylvania and Ohio -- did so entirely through the legislative process. Furthermore, public support for nationwide legalization tied an all-time high in Gallup's 2015 poll at 58%.

People in nine states, including California, Florida and Massachusetts, will vote Nov. 8 on ballot proposals permitting recreational or medical use of marijuana. These initiatives could give a big push to legalization, prompting the next president and Congress to overhaul the country’s failed drug laws.

This is a big moment for what was a fringe movement a few years ago. A Gallup poll released on Wednesday showed 60 percent of Americans support legalizing marijuana, up from 31 percent in 2000 and 12 percent in 1969.

Business owners are replacing idealists in the pot-legalization movement as the nascent marijuana industry creates a broad base of new donors, many of them entrepreneurs willing to spend to change drug policy.

Unlike in the past, these supporters are not limited to a few wealthy people seeking change for personal reasons. They constitute a bigger coalition of business interests. And their support provides a significant financial advantage for pro-legalization campaigns.

“It’s mainly a social-justice movement. But undoubtedly there are business interests at work, which is new in this movement,” said Kayvan Khalatbari, a one-time pot-shop owner and now head of a Denver marijuana consulting firm.