The United States is a vast and growing marijuana market, both for illicit vendors and, increasingly, legitimate producers. Ever since 2012, when Colorado and Washington took the plunge, U.S. states have been legalizing cannabis at a rapid pace. Although recreational cannabis is only legal in 10 states right now, medical marijuana is legal in 33, making the legitimate U.S. market a sizable one. And with many more states considering legalization, it’s set to grow larger.

The marijuana industry has been growing like a weed for years, but it brought something new to the table in 2018: legitimacy.

Following years of promises from Canadian Prime Minister Justin Trudeau, and months of debate in the Senate, Canada became the first industrialized country to give the green light to adult-use weed in June, with sales officially beginning on Oct. 17, 2018. Rolling out the red carpet for cannabis signifies that this is a valid business model that could potentially make investors very rich over the long run.

The marijuana industry recently put the finishing touches on what was its most defining year ever. In 2018, Canada became the first industrialized country in the world, and only the second country overall behind Uruguay, to legalize recreational cannabis. In doing so, Canada opened the door to billions of dollars in added annual sales and, more importantly, declared the legal pot industry a legitimate business model.

Much of the excitement in the world of marijuana stocks focused on Canada in 2018. But that could change with the new year. Investors might want to look more to the U.S. in 2019 for several reasons.

The legalization of hemp (which, by definition, is cannabis that contains low levels of psychoactive compound THC) could open the way for a much larger hemp-based cannabidiol (CBD) market in the U.S.

Several new marijuana markets in U.S. states should mature in 2019 -- with new markets also launching in other states. And there's a distinct possibility that efforts to revise federal laws to recognize the authority of the individual states to enforce their own marijuana laws could succeed.

Canada has a legal and regulated pot industry, but some of the best weed in the world is still grown just south of the border in the United States.

The status of cannabis component CBD as a trendy new superfood ingredient may be cemented this week by U.S. President Donald Trump.

The US$867 billion farm bill, headed to the president for his signature, would remove industrial hemp from a list of federally controlled substances, a major step as weed culture pushes into the U.S. mainstream. That would create a legal market for CBD that could be worth more than US$20 billion by 2022, according to research firm Brightfield Group.

“This is nothing short of seismic for the cannabis industry,” said Kristen Nichols, editor of the trade publication Hemp Industry Daily. “All the obstacles that cannabis faces stem from it being federally illegal.”

A game changer for the cannabis industry is quietly being pushed through the U.S. political system. It’s something that’s barely getting any media attention, but could be a much bigger boon to cannabis producers than this year’s ill-fated legalization drama.

What I’m talking about is the federal-level legalization of hemp in the U.S.

The Canadian cannabis producer Canopy Growth expects to enter the US market by the end of 2019, according to analysts at Cowen.

Speaking at a New York City-based Contractors Association Lunch on Tuesday, Canopy CEO Bruce Linton said he expects his company to have an active presence in the US cannabis market by late 2019, Cowen says.

Here's a quick trivia question for you: What are the three largest U.S.-based marijuana stocks by market cap? If your answers included MariMed (NASDAQOTH:MRMD) and MedMen(NASDAQOTH:MMNFF), pat yourself on the back. (The third correct answer -- and the biggest of them all -- is Scotts Miracle-Gro.)

The marijuana industry has truly been something special this year.

For starters, Canada became the first industrialized country in the world to legalize recreational cannabis on Oct. 17. When the industry is fully up to speed, Wall Street believes it could be generating in excess of $5 billion in annual added sales, atop what it was already bringing in from medical weed sales and exports to medically legalized foreign countries.