Even though it hasn't exactly been the best year for marijuana stocks, cannabis is still projected to be one of the fastest-growing industries over the next decade. Worldwide weed sales have more than tripled, from $3.4 billion to $10.9 billion between 2014 and 2018, and Wall Street has forecast that sales will grow to between $50 billion and $200 billion by 2030.

Yet make no mistake about it: This growth story is all about the United States. Nearly all estimates on Wall Street suggest that the U.S. will account for a third to a half of all global sales by the end of the upcoming decade. That makes the U.S. the crown jewel of the cannabis movement.

These states have fully embraced the green rush

However, we're already seeing some impressive revenue totals being put up by a number of medical and recreationally legal U.S. states. According to estimates provided by Arcview Market Research and BDS Analytics in their 2019 State of the Legal Cannabis Markets report, there are five states expected to hit the psychologically important $1 billion sales mark in 2019 and 10 that'll produce, at minimum, $298 million in estimated 2019 pot revenue. Let's take a closer look at the 10 most important cannabis states, at least in 2019.

Listed in descending order by projected revenue, the top-selling marijuana states in 2019 are:

  1. California: $3.1 billion (not broken down into a recreational and medical component)
  2. Colorado: $1.6 billion ($1.3 billion recreational, $0.3 billion medical)
  3. Washington: $1.1 billion (not broken down into a recreational and medical component)
  4. Florida: $1 billion (all medical marijuana)
  5. Michigan: $1 billion (all medical marijuana)
  6. Nevada: $770 million ($700 million recreational, $70 million medical)
  7. Oregon: $752 million ($707 million recreational, $45 million medical)
  8. Arizona: $705 million (all medical marijuana)
  9. Massachusetts: $484 million ($250 million recreational, $234 million medical)
  10. Pennsylvania: $298 million (all medical marijuana)

You'll note that Michigan is listed as entirely medical, despite the fact that it surprised everyone by opening its doors to adult-use weed sales on Dec. 1, 2019, about four months earlier than anyone expected. The State of the Legal Cannabis Markets was published many months before Michigan regulators made this decision, so that's why you see only medical marijuana sales expected in the Wolverine State.

Marijuana stocks are flocking to many of these states

Although not every state is inviting to privately held multistate operators (MSO), a number of these core markets are highly sought after by vertically integrated MSOs.

As you might imagine, pretty much every MSO wants its piece of the California market. MedMen Enterprises (OTC:MMNFF) , whose California locations have rivaled Apple stores in terms of sales per square foot, has opened up more than a dozen retail locations in the Golden State. Unfortunately for MedMen and its peers, it's been anything but smooth sailing.

An aggregate tax rate that could be anywhere from 50% to 80%, by some estimates, continues to drive consumers back to black-market retailers. As a result, statewide legal sales between 2017 and 2019 are only expected to increase by a meager 3%. This is a big reason why MedMen's sequential quarterly sales growth has slowed, and why the company has been losing money at an extraordinary pace.

Perhaps the most successful state-level market is Florida. The Sunshine State only issued vertically integrated operating licenses to a little over one dozen companies, but did so quickly enough to allow these businesses ample time to build up a sizable retail presence.

Trulieve Cannabis (OTC:TCNNF) , for example, has opened 40 stores in Florida and placed most of its emphasis on building its brand within the state. Even though Florida only allows the sale of medical marijuana, Trulieve has found plenty of success and is, hands down, the most profitable pot stock on the planet right now. With Florida potentially looking to legalize recreational cannabis in 2020, Trulieve's existing retail presence puts it in good position to succeed.

Don't overlook Nevada, either. Even though Nevada is only expected to generate the sixth-highest sales in 2019, by 2024, per-capita spending on cannabis is forecast to be the highest in the country (thanks, tourism!).

Nevada's rapid ascent in the post-adult-use legalization environment is what encouraged Planet 13 Holdings (OTC:PLNHF) to open up a retail shop like nothing we've ever seen before. The Planet 13 SuperStore just west of the Las Vegas Strip will span 112,000 square feet when complete and house everything from a consumer-facing processing center to a coffee shop and pizzeria. The experience Planet 13 can provide is unparalleled, and the fact that this single store is accounting for 9% of Nevada's total weed sales is proof.

Watch these states in 2020

Naturally, with the calendar just weeks away from changing over to a new year and new decade, attention is also being placed on a handful of states that could make some noise in 2020.

Michigan and Illinois are certainly worth keeping a watchful eye on given that the Wolverine State kicked off adult-use sales on Dec. 1, and the Land of Lincoln will do the same on Jan. 1, 2020. Both should be billion-dollar, top-10 markets by total sales in the U.S. by 2024, and vertically integrated MSOs have been particularly active of late in setting up shop in anticipation of these legalizations.

Illinois is a particularly interesting case given that all MSOs are limited to just 10 retail stores in the state and a vast majority of municipalities in the state aren't allowing dispensaries to sell adult-use weed. This has all the makings of a supply deficiency that promotes black-market sales. I wouldn't be in the least surprised if Illinois regulators aren't forced to act to protect their legal industry.

I'd also expect Arizona to really come into focus in 2020. For those of you who may not recall, Arizona was the lone state in 2016 that wasn't able to get its recreational marijuana measure (Proposition 205) approved. However, cannabis groups focused on legalization have really been devoting time in Arizona ahead of an initiative that'll aim to legalize adult-use weed in 2020.

We've seen that the second time is often the charm when it comes to recreational legalization, as it was in California and Oregon. Thus, I'd look for Arizona to become a recreationally legal state in November and for pot businesses to set up shop in what could be a very lucrative cannabis state.

No matter what happens, 2020 is bound to be an exciting year for the U.S. marijuana industry.

This article originally appeared in the Motley Fool.

Sean Williams has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has a disclosure policy.