Our neighbor to the north is sparking a green revolution. No, not energy. Weed.

In April, Canada’s federal government started allowing a handful of private companies to grow and sell medical marijuana on a massive scale.

There aren’t any storefronts or local dispensaries in the Great White North. All marijuana is shipped via registered mail. Once you’ve obtained your recommendation from a physician, you register with a provider, and your buds get mailed to your door.

That’s a sharp contrast with the U.S., where medical and recreational marijuana is still federally banned, states have differing medical marijuana laws, and where it’s permitted, patients have to trudge to their local dispensary to get their prescription filled.

Twenty-one states and D.C have medical marijuana laws on the books. All pot companies are constrained to sales within their state, and they operate with a degree of uncertainty. At any time, the federal government could choose to enforce their longstanding position that marijuana is a no-no.

Canada’s medical marijuana laws resemble some of the more liberal states – such as California or Maine – in that they allow all physicians to recommend cannabis as treatment for any condition they deem necessary.

Medical weed in Canada is nothing new – it’s been legal since early 2001 – but who grows and sells it is new.

Originally, these patients received marijuana from the government and also had the option of growing it on their own. Over the years the roster grew from 500 patients to over 40,000. Every patient who wanted medical weed had to apply with Health Canada, the federal agency that oversees the nation’s health laws.

The Canadian government realized their existing rules weren’t set up for that level of scale. Keeping track of tens of thousands who were using and possibly growing medical marijuana proved to be a nightmare.

There were also safety and health concerns. People enjoyed a lot of freedom growing their own plants, but there was no practical way of knowing what conditions they were growing in, who they were growing for, or what products they were using on their crops.

So Health Canada decided to change things and now issues licenses to private companies who grow cannabis in commercial facilities and sell it nationwide.

The rules heavily moderate the companies and their facilities, allowing the government to audit them at any time and make surprise visits to make sure they’re up to code.

One pioneer, Tweed Inc., purchased a former Hershey’s chocolate factory in Smiths Falls, Ontario, and is now one of the leading providers of medical marijuana in Canada.

Business is booming.

“Having a completely legal framework from the federal government down to the provincial level, as well as municipal, allows us to deal with banks,” Chuck Rifici, CEO and Co-Founder of Tweed Inc. told Fusion. “It’s like a regular business here.”

Because there are no retail operations, every medical marijuana company is competing for the entire Canadian market, giving them access to whomever is in need of medical cannabis among their thirty-five million citizens.

Once a patient has obtained their recommendation from their doctor, they have to register with one of the companies authorized to sell marijuana, then order exclusively from them. Currently, there are 13 licensed providers, with hundreds of applications pending.

Tweed is publically traded on the Toronto Stock Exchange and is currently valued at over $100 million. Estimates suggest the industry as a whole could be worth $1.2 billion within the decade.

Rifici, 39, said there were many reasons why Tweed decided to go public. Part of it was trying to shake the perception that medical marijuana is taboo.

“We’re not allowed to advertise in this industry. In Canada it’s a controlled substance, it’s treated very much like a narcotic,” Rifici said. “Mainly, it’s about trust. I think one aspect of trust if we’re a public company is you know the disclosure and transparency that comes with that.”

In many ways, the industry resembles Amazon. The absence of retail locations allows providers to ship directly to their customers from factories and warehouses located across the country.

“We have a storefront, e-commerce site,” Rifici said. “People can order or reorder their marijuana using their iPhones, on a tablet or on the web, or on the phone.”

Along with nationwide availability, there are some limitations.

The new rules say you can’t grow your own plants. But patients protested that restriction and an injunction was issued in March that temporarily allowed patients to keep growing their own weed until the courts have a chance to review the changes next year.

Also, if you’re into weed-laced cookies, brownies, beverages and oils you are out of luck; Canada doesn’t allow the sale of those products, so you’ll have to make them on your own.

Thinking ahead, regulators made rules that would govern the import and export of cannabis in the eventual global medical marijuana market. But of course, it has to be legal in the other countries first.

“If the U.S. ever changed on a federal level, we would then be able to have import and export opportunities with U.S. companies,” Rifici said. “But there’s obviously a lot behind that.”

Unfortunately for green entrepreneurs, political barriers in the U.S. remain. The federal government has yet to consider any fundamental changes to their laws.

With green building up across our border, Canada might be schooling its neighbors in something besides hockey.

Related: Fusion’s Jorge Ramos spoke with producer Daniel Clark about this story: