When searching for America's fastest-growing industries, chances are you'll find marijuana near, or at, the top. Cannabis research firm ArcView pegged legal sales of the drug at $5.4 billion in 2015 and believes the legal industry can grow organically by 30% per year through 2020. This would bring legal sales for the industry to nearly $22 billion if this estimate were to come to fruition.

Marijuana's success is mostly based on the expected expansion at the state level. For those who may not have been following the recent events surrounding cannabis, the U.S. Drug Enforcement Agency, with the assistance of the Department of Health and Human Services, declined to reschedule marijuana from its current schedule 1 status. This move effectively leaves marijuana as an illegal substance at the federal level and implies that it has no medical benefits. In other words, the only way the cannabis industry has any chance of growth is through state-level expansion via ballot measure or legislative approval.

As we head into November, residents in nine states are readying to vote on a legal marijuana initiative. Five states -- California, Maine, Nevada, Massachusetts, and Arizona -- will be voting on whether to legalize recreational marijuana for adults aged 21 and up, while four additional states -- Montana, North Dakota, Florida, and Arkansas -- will be attempting to legalize medical marijuana. There are currently 25 states that have legalized medical marijuana and just four, along with Washington, D.C., that have legalized recreational marijuana.

Three states that could vote against legalizing marijuana

With national pollster Gallup's latest poll showing support for nationwide legalization at 58%, and CBS News' poll in 2015 showing 84% support for legalizing medical marijuana, you'd think an approval would be a slam-dunk in all nine states. However, based on select poll results, three states could wind up rejecting their respective marijuana initiative or amendment.

Arizona

All eyes are going to be on Proposition 205 in Arizona, which received more than 250,000 signatures to get on the November ballot. If approved, adults ages 21 and up would be able to possess up to 1 ounce of marijuana, grow up to six plants, and consume marijuana in non-public places. Recreational marijuana would carry a 15% tax rate.

Now here's where things get a bit dicey. In July, a survey taken by O.H. Predictive Insights showed that 39% of Arizonans favored the measure, 52.5% planned to vote no, and roughly 8.5% remained undecided. Though there were pockets of favorability toward Prop 205 in select counties, the measure was (at least based on this poll) slated to lose. Mike Noble, the managing partner and chief pollster of O.H. Predictive Insights, pegged the higher propensity of Arizona's older population to vote, and seniors' general dislike for marijuana, as the reason it would likely fail.

A more recent poll conducted by the Arizona Republic found 50% in favor of Prop 205, compared with 40% who opposed it and 10% who remained undecided. This poll was conducted in late August and surveyed just shy of 800 people.

Though the polling data is conflicting, it's possible supporters' dream of legal recreational marijuana in Arizona could go up in smoke.

Massachusetts

Another state that could be a complete toss-up is Massachusetts, which is bringing Question 4 to its residents this November. If approved, Massachusetts would allow adults 21 and over to possess up to an ounce of marijuana, have up to 10 ounces in their homes, and grow up to six plants. In terms of taxation, The Regulation and Taxation of Marijuana Act, as it's officially known, would add a 3.75% tax on top of the state's 6.25% sales tax, and local taxes could add up to an additional 2%. Cities could also have the option to ban legal marijuana commerce, which would be similar to what we've seen happen in Colorado with more than half of all jurisdictions still banning the drug following its 2012 approval.

However, an approval in Massachusetts seems to be far from a guarantee. As reported by The Boston Globe, a July 12-13 poll conducted by Gravis Marketing for Jobs First of 901 registered voters showed that 51% planned to vote against Question 4, 41% were in favor of Question 4, and 9% remained undecided.

Yet, just as we saw with Arizona, a more recent poll suggests that public opinion may have reversed. The WBUR/MassINC poll conducted in early September showed that 50% of the 506 likely voters favored Question 4, compared with 45% who opposed it.

It's looking as if the pendulum could swing either way on cannabis in Massachusetts this November.

North Dakota

Finally, residents of North Dakota will go to the polls in November to vote on the North Dakota Compassionate Care Act, which would legalized medical marijuana in the state. Also known as Initiated Statutory Measure No. 5, the Act would allow for the possession of up to three ounces of cannabis for qualifying conditions such as cancer, glaucoma, epilepsy, and AIDS, and it would allow residents to grow up to eight plants if they live more than 40 miles from a licensed dispensary within the state.

Whether a medical marijuana law sees the light of day in North Dakota, though, remains up for debate. In 2014, Forum Communications Co. commissioned a poll conducted by the University of North Dakota College of Business and Public Administration to get a feel for North Dakotans views on medical marijuana. Though 47% supported legalizing medical marijuana compared with 41% who opposed it, those who strongly opposed it (35%) slightly outnumbered those who strongly support (33%) the idea.

As a relatively non-populous state polls are somewhat hard to come by, and I would deem there to be enough of a margin of doubt in this data to suggest North Dakota could wind up rejecting its medical-cannabis measure.

This outcome could be a given

While the aforementioned three states could be a complete toss-up, the one given this election cycle is that it's still far too early for investors to consider marijuana as a viable, long-term investment opportunity. Even with expansion at the state level, restrictions caused by the drugs' schedule 1 status will likely make it tough for investors to earn much, if at all, investing in marijuana stocks.

Let's not forget that there are two major drawbacks for cannabis-based businesses as long as the drug remains as schedule 1. For starters, businesses in the cannabis industry have virtually no access to basic banking services. Just 3% of all banks in the U.S. are currently working with marijuana businesses, with many choosing to simply stay on the sidelines rather than risk possible federal prosecution down the line.

Marijuana businesses also face tax disadvantages. U.S. tax code 280E disallows businesses from taking normal business deductions when selling a federally illegal substance. This leaves marijuana businesses to pay tax on their gross profits instead of net profits.

The investing environment just isn't that friendly yet, which should give you all the more reason to watch from the sidelines for the time being.