There are expected to be a number of fast-growing trends this decade, including cloud computing, the Internet of Things, artificial intelligence, and cybersecurity. But don't sleep on marijuana.

After generating an estimated $10.9 billion in worldwide sales in 2018, legal channel cannabis sales are expected to hit anywhere from $50 billion to $200 billion a year by 2030, according to various Wall Street estimates. Yes, this is a pretty wide range, but it's to be expected of an industry that's never been legalized in the modern era, and which has tens of billions of dollar in activity occurring behind the scenes.

It's also an industry that could soon get a lot bigger in the United States. Currently, two-thirds of all states have given the green light to medical marijuana, with 11 of these states also allowing for the consumption and/or retail sale of adult-use weed. But in less than a month, we could see these figures tick higher.

The Nov. 3 election will feature five states with cannabis measures on their respective ballots. However, none is going to be more unique than what the Mount Rushmore State is presenting to its residents.

A black silhouette outline of the U.S., partially filled in by cannabis baggies, rolled joints, and a scale.

Image source: Getty Images.

The Mount Rushmore State is four weeks away from making cannabis history

While we've witnessed a number of unlikely ballot measures before, South Dakota is about to do something no state has previously attempted: It's trying to legalize medical and recreational marijuana at the same time, albeit with two separate ballot measures.

First up, Mount Rushmore State voters will have to weigh in on Measure 26, which would establish a medical marijuana industry in the state for patients with predefined debilitating medical conditions. The measure would allow qualifying patients to possess up to three ounces of cannabis, as well as grow at least three cannabis plants at their residence, as prescribed by a physician.

Initially, Measure 26 would include severe nausea, seizures, and severe or persistent muscle spasms among the list of qualifying debilitating medical conditions. However, South Dakota's Department of Health would be free to add to the list of qualifying conditions upon passage of the measure. 

Secondly, South Dakotans will also being voting on Constitutional Amendment A, which would legalize recreational marijuana throughout the state. Pretty much in-line with what we've seen in other adult-use-legal states, South Dakota will establish a legal age for consumption and possession of 21, and (more specific to the state) will assign a 15% tax rate on weed sales.

What's interesting about the recreational legalization measure is that it doesn't establish a medical marijuana program or provide hemp guidelines in the state. This means the South Dakota State Legislature would be responsible coming up with the rules and regulations governing a medical cannabis and hemp industry by or before April 1, 2022. 

Considering that we have no precedent of a state jumping from wholly illicit to recreationally legal, I'm not certain Amendment A will pass. But favorability toward medical marijuana is high (pardon the pun), making passage of Measure 26 fairly likely.

Multiple voting booths partitioned off, with attached voter pamphlets.

Image source: Getty Images.

Four other states will join South Dakota on Election Day

In addition to South Dakota, four other states will by vying to go green.

The only currently illicit state (other than South Dakota) that's attempting to legalize medical marijuana is Mississippi. The Magnolia State has a two-part cannabis question on its ballot that'll require residents to first assess their palatability to medical marijuana, and secondly choose which type of medical cannabis program they prefer. Initiative 65 is a more traditional program that allows physicians to prescribe cannabis for 20 qualifying conditions. Meanwhile, Initiative 65A restricts the smoking of medical marijuana to patients with terminal illnesses and provides increased regulatory oversight.

The other three states – New Jersey, Arizona, and Montana – are all voting on recreational pot initiatives.

New Jersey was the first state to get a measure firmly on the ballot for the November election. Polling has suggested that Public Question 1 has a good chance to pass. As a reminder, New Jersey's legislature was very close to waving the green flag on recreational weed in early 2019, but was ultimately derailed by social measures. Residents will instead get to decide the Garden State's fate in a little over four weeks.

Similar to New Jersey, Arizona seems to have an above-average opportunity to legalize adult-use cannabis. Arizona narrowly voted down Proposition 205 in Nov. 2016 (48.7% in favor), which would have legalized recreational weed in the Grand Canyon State. History has shown that the second time is the charm when it comes to recreational legalization measures.

Montanans will also have two measures they'll be voting on, both of which work toward the same goal. Montana Cl-118, if passed, would allow the states' constitution to be amended, making 21 the legal age of cannabis purchase, use, and possession. Then there's I-190, the actual adult-use pot measure that would impose a 20% tax rate if passed. Of the three recreational-only votes, Montana should be the most closely contested.

Multiple labeled jars packed with unique dried cannabis buds on a dispensary countertop.

Image source: Getty Images.

U.S. multistate operators should have a field day

No matter what happens with the presidency come Nov. 3, there's a very good chance the number of legalized recreational and/or medical marijuana states will increase. With the federal government maintaining a hands-off approach to regulation (i.e., allowing states to regulate their own pot industries), U.S. multistate operators (MSO) appear primed to have a field day in 2021.

In particular, some of the largest publicly traded MSOs are in great shape to benefit from new legalizations and ongoing organic expansion in legalized states. For instance, Curaleaf (OTC:CURLF) recently closed its acquisition of Grassroots, which has increased its operating retail locations to 93, and bumped up its presence to 23 states. Curaleaf has an existing presence in New Jersey, and looks to be on track to hit $1 billion in full-year sales by 2021.

Green Thumb Industries (OTC:GTBIF) will also see a bump-up in sales, but not solely because of newly legalized states. Though Green Thumb has a presence in New Jersey, it's Nevada and Illinois that can be even more lucrative markets from an organic growth perspective. Green Thumb currently has 48 open dispensaries, but holds enough licenses to double this figure.

Investors often love to follow the money to big gains -- and it's pretty evident that, when it comes to marijuana stocks, the U.S. is where the green will be freely flowing.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.