As voters in Arizona, California, Maine, Massachusetts, and Nevada get ready to vote for recreational marijuana on Election Day in November, support for legal marijuana use among American adults has risen to 60 percent, according to a new survey by Gallup. This is the highest percentage of support the polling firm has seen for the federally-illegal drug. In 2013, a year after Colorado and Washington voted to approve recreational sales, nationwide support just surpassed 50 percent.

Currently, only four states and Washington, D.C. have legal recreational markets, representing only 5 percent of the American population which lives in a state where adult pot use is legal. If all five states vote yes for legalization in November, that number will rise to 25 percent. In particular, if California--a political trend-setting state that influences the country's progressive changes--opts to legalize, it could be a matter of time until it is legalized nationally. "It is possible that it might take a Supreme Court case to settle this matter, too," writes Art Swift, managing editor at Gallup.

Gallup says the shift in public attitudes towards legal marijuana "has mirrored" the acceptance and legalization of same-sex marriage, which the U.S. Supreme Court made legal last year. The polling firm first asked Americans if they supported legal cannabis use in 1969; at the time, only 12 percent said yes. By the late 1970's, support rose to 28 percent, before dropping again during Nancy Reagan's "Just Say No" campaign. But in 2000, support for legal marijuana reached 31 percent and has continued to grow each year.

Gallup has also found that the demographics of legalization support has broadened, chiefly among Republicans and older Americans. Sixty-seven percent of Democrats support legal use, up from 38 percent in 2005, while 70 percent of Independent voters support legalization, up from 46 percent in 2005. But the percentage of Republicans who support legal use has doubled over the last ten years, from 20 percent in 2005 to 42 percent of Republicans in 2016. The shift in attitudes is also not limited to young Americans--support for legalization is up among all age groups in the past decade. Only 29 percent of people 55 and over supported legal use in 2005 and now 45 percent of that age group support it. Sixty-one percent of people 35 to 54 support legal use and 77 percent of 18- to 34-year-olds favor legalization.

Tom Angell, the chair of pro-legalization group Marijuana Majority, says momentum needs to continue. "More politicians -- presidential candidates included -- would do themselves a big favor to take note of the clear trend and then vocally support legislation catering to the growing majority of Americans who support modernizing failed marijuana policies," says Angell.

As for the impact on entrepreneurship, more legal markets across the nation would help further legitimize the industry and create more opportunity for entrepreneurs. All eyes are on California, which was the first state to legalize medical marijuana in 1996 but has been slow to adopt clear and specific rules and regulations. The lack of regulations like mandatory testing, outlines on legal processes for transporting product and other areas, created a giant market, California is estimated to produce 80 percent of all marijuana grown in the U.S., without the rules and structure of states like Colorado. Basically, dispensaries and consumers were protected under state law, but growers, distributors and transporters fell in a gray area. More legal structure for the nation's biggest market will go a long way in legitimizing the industry.

Rob Hunt, founding partner of marijuana-focused private equity firm Tuatara Capital, which backs Willie Nelson's marijuana brand Willie's Reserve, says if the ballot measure pass in each state a new and lucrative industry will be created that will start producing tax revenue and create jobs. But the largest impact, says Hunt, who is also the president of Teewinot, biopharmaceutical company that manufactures cannabinoid-based therapies, is that five more states with legal markets could be a tipping point:

"The aggregate effect of this election is that it will force the federal government to reexamine its position on cannabis policy," says Hunt. "There remains little doubt that cannabinoid based medications present an entirely new category of medicines to be investigated by forward thinking drug developers and that the American electorate is supportive of this progression."