The widespread use of cannabis to make rope, sails, and textiles made it an important driver of economic growth in the past, but recreational and medical marijuana could represent an even bigger market opportunity in the future.

In this clip from The Motley Fool's Industry Focus: Healthcare, analyst Kristine Harjes and contributor Todd Campbell discuss marijuana's past and update investors on legalization efforts worldwide.

A full transcript follows the video.

This video was recorded on Aug. 1, 2018.

Todd Campbell: For context, to help our listeners, I was going through and looking at some of the history of cannabis. I came across some really fascinating factoids that I felt like our listeners could share over cocktails with their friends this weekend and impress everybody.

Kristine Harjes: Let's hear them!

Campbell: Did you know, they have found cannabis seeds in the graves of people in Siberia and Asia going back to 500 BC?

Harjes: I can't believe they last that long.

Campbell: Right. Notice that they didn't say what they did with the seeds after they found them. [laughs] But, obviously, showing that cannabis seeds were very revered, even as far back as that. Really, the industrial use of cannabis stretches even further back than that. They've found Chinese pottery that has impressions that were likely made by hemp rope. Hemp is also part of Cannabis sativa, which is the plant responsible for marijuana, going back to 5,000 BC -- we're talking over 7,000 years of use, at least from the industrial side of things. It's not just in Asia where there's a long history of using cannabis. We also have a pretty long history of using cannabis, specifically hemp, here in the United States, too.

Harjes: Do you have a fun factoid for U.S. use?

Campbell: I certainly do! [laughs]

Harjes: How did I know? [laughs]

Campbell: Did you know, the American colonists, the immigrants from the United Kingdom, when they were sent over, the colonists were actually required to grow hemp on some of their farmland? That was because hemp can produce fibers that are incredibly strong and important in creating rope and sails. A big driver of the economy, being able to transport goods back and forth across the ocean. Going all the way back to, prior to the formation of our country, we've been using cannabis, at least for industrial purposes. Actually, at one point, you could actually pay your tax bill in hemp.

Harjes: No way!

Campbell: Yeah! Thomas Jefferson dedicated one acre of his "best ground" on the Poplar Forest estate to the production of hemp.

Harjes: That's crazy. I had no idea, any of those historical factoids.

Campbell: A very long history. Again, this is a healthcare show, so we're tilting toward the use of it medicinally. Even there, there's a pretty long history. You go back to the late 1800s, and it was incredibly common to just walk into a pharmacy or a store and be able to buy cannabis extracts for the use of treating stomach ailments, all throughout the late 1800s.

Harjes: Even given this tenured history, it seems like we're hitting a tipping point now, or in the last few years, at least. Public support for marijuana, both from a medicinal perspective and a recreational perspective, is at an all-time high. Support for medical use in the United States is almost universal. There was a recent poll that put that figure at, 94% of Americans would support medicinal legalization of marijuana.

Really, it's for use in fairly specific ways that has proven to people that it can actually do some good for reasons that are so far away from the perception that people used to have of it being some hippie drug. There's a genuine medical use for children with epilepsy and cancer patients with pain. I think the increasing use of medical marijuana in these very legitimate ways has changed people's perceptions of it.

And as support for medical marijuana grows, support for recreational seems to follow. In October 2017, a Gallup poll showed 64% of Americans supporting full legalization. It crosses into both sides of the aisle, making it one of the few issues that has majority support from both Democrats and Republicans.

Campbell: Right. It still remains illegal on a federal level, but a lot of states now are waking up and listening to their constituents and passing laws that at least ease the way to gaining access to its use medically. There's a lot of anecdotal evidence over the years. We go back, like I told you, to the late 1800s, there was anecdotal evidence that supported the use of it in stomach ailments. Anecdotal evidence has been out there for its use in treating cancer and pain. Recently, which I'm sure we're going to talk about later in the show, there was an FDA approval that we talked about a couple of weeks ago on our podcast, of a drug for use in epilepsy that's actually based on one of the chemical cannabinoids in marijuana.

I think that's one of the things that our listeners need to know. What exactly is marijuana? It's the dried flower from the female form of the Cannabis sativa plant. It's comprised of over a hundred different chemical cannabinoids. The two that are most prevalent, are found most often within that flower, are going to be THC, which is the one responsible for that euphoric high, and CBD, which is a non-psychoactive chemical cannabinoid which has been found, anecdotally, and now with this other drug that just got approved, to be helpful in treating patients with conditions such as epilepsy.

Harjes: Even though all of those cannabinoids are illegal in the United States at a federal level, there are legal and practical reasons why it's been left to states to determine whether they want to allow it. As of today, medicinal use is legal in 30 states, including nine states in which recreational use is also approved.

Campbell: Right. Oklahoma just passed a medical marijuana bill in June, that brought it to 30. Vermont's law for recreational just went into effect in July, which brought that total to nine. Still the minority for recreational use, but definitely a growing momentum nationwide to at least allow its use medically. In many cases, that's going to be for the use of CBD-high strains of marijuana, not high strains of THC, which is the one that causes the high.

Harjes: I think one interesting case study is California, which was actually the first state to approve medicinal marijuana use back in 1996. They just started recreational sales earlier this year. I think it was surprising that other states beat them there, as far as the timeline goes.

There's an enormous market in California. There's estimated to be an enormous number of sales, up to $7.6 billion in 2022. That's up from an estimated $4.2 billion in marijuana sales last year. So, growing from $4.2 billion last year to $7.6 in 2022, that's some pretty crazy growth, and it's going to lead to pretty significant tax revenue, as well. And that's one of the biggest reasons why, politically, people are making the argument to their representatives that this is a good thing to do.

Campbell: Prior to the show, I was talking to Matt Karnes over at GreenWave Advisors. There are a lot of different estimates that are out there about how big these markets could be, so listeners need to take it with a grain of salt. Recognize that it could be lower or higher, who knows how it'll all play out. We do have some evidence. I'm sure we'll talk about Colorado in a second.

But, GreenWave is saying $7.6 billion by 2022. And California is the Big Kahuna. 34% of the U.S. market share for marijuana sales is California, and perhaps that's one of the reasons that the Emerald Triangle in California is one of the largest producing areas or regions in the country of marijuana.

Harjes: You mentioned Colorado. That's another huge market. Sales of marijuana there in 2017 topped $1.5 billion. Fun factoid about Colorado, there are more marijuana dispensaries than Starbucks and McDonald's locations combined, which is just insane.

Campbell: That'll impress friends over the weekend, when you tell them that statistic, right?

Harjes: Yeah, write that one down.

Campbell: Absolutely. Colorado and Washington became the first two states to fully legalize marijuana. They did that in 2012. California had been the first state to approve medicinal use, of it, but that happened in 1996. Colorado was a pioneer in the recreational market.

I think one of the things that a lot of these states are looking at, one of the reasons that you have across-the-aisle support for legalizing marijuana, is that it provides a lot of funding for these states' budgets. Just look at Colorado's experience. They went from collecting $67 million in fees back in 2014, to, so far, in the six months of this calendar year in 2018, over $130 million. Their revenue from marijuana sales has just about doubled in the span of a few years in Colorado.

Harjes: Meanwhile, if you look internationally, the Cannabis Act, which regulated recreational use of marijuana, was passed by the Canadian Senate on June 21st of this year. Prime Minister Justin Trudeau expects that consumption will begin on October 17th. That's coming up very quickly. This is noteworthy because Canada is the first major country to take this step of fully legalizing marijuana. There's actually one other country in the world that beat them to that, and that is Uruguay.

Then, over in Europe, you have a large, growing market in Germany, which legalized medicinal marijuana back in March of 2017. Many suppliers already have a presence in Germany via their partnerships and acquisitions. People are definitely keeping an eye on Europe, in particular, Germany. There's also a huge market in Australia, where medical marijuana has been legal for two years, and possession is mostly decriminalized. There are places all over the world that are embracing marijuana increasingly.

Campbell: As I was going through, I found at least 26 countries that either have lax laws when it comes to marijuana, meaning it's decriminalized, or they outright say it's OK to possess limited amounts of it. You mentioned Canada. Canada is by far the most progressive. They've had that recreational market opened nationally for years. It's the biggest legal market out there, as far as countries go, and it's going to get even bigger later into the year.

I'd also be keeping an eye on a couple of other countries, too. I'd keep an eye on Mexico. It's still illegal in Mexico, but there has been some chatter with the new Administration that got elected there to at least consider approving medicinal use. I'd also keep an eye on Great Britain. Great Britain has some of the strictest marijuana laws out there, but they recently ordered a review of their approach to medicinal marijuana, following an event back in June where marijuana was seized from a boy who was using it to treat epilepsy, who was then later hospitalized because of seizures. So, they're reviewing their approach to it.

I think this is a global push toward legalizing marijuana, and I think that's why so many of our listeners and the visitors to are interested in learning more about it and finding out whether or not there are investment opportunities they can take advantage of.

Kristine Harjes has no position in any of the stocks mentioned. Todd Campbell has no position in any of the stocks mentioned. His clients may have positions in the companies mentioned. The Motley Fool owns shares of and recommends SBUX. The Motley Fool has a disclosure policy.