The legal-marijuana industry is on one heck of a run. Last year, five states legalized the use of medical cannabis for select ailments, pushing the number of states that have chosen to allow physicians to prescribe cannabis past the halfway mark (28 states). We also witnessed the number of recreational-pot states double to eight from four.

The result has been a steady increase in North American legal weed sales (including Canada, which legalized medical marijuana back in 2001). Cannabis-research firm Arcview estimated a 34% increase in North American legal sales to $6.9 billion last year alone.

Marijuana hits a federal ceiling

Despite this strong growth, the marijuana industry faces a number of major impediments, many of which relate to its illegal status at the federal level. Pot's Schedule I categorization means it's an illicit drug that's deemed to have no medical benefits.

It also means weed businesses are subject to a handful of serious disadvantages compared to "normal" businesses. For instance, marijuana-based companies struggle to obtain basic banking services from financial institutions, forcing many to deal in cash only. Also, weed-based companies aren't able to take normal corporate income tax deductions since they're selling a federally illegal substance, leading to them paying tax on their gross profits instead of net profits.

Congress, for its part, has moved with the swiftness of molasses in winter in addressing the rapidly changing public opinion on marijuana. Gallup and CBS News polls show that support for nationwide legalization is at an all-time high of 60% and 61%, respectively.

11 high-profile people in favor of legalizing marijuana

This means it's up to prominent, highly influential people to keep the legalization movement in the limelight and on the doorstep of Congress.

Just as retailers hire well-known athletes, celebrities, and public figures to represent their brands and encourage engagement with consumers, the pot industry is counting on prominent people to be their "brand ambassadors" to take the fight to Washington.

Here are 11 of the most highly influential people who've weighed in on medical and/or recreational marijuana, and voiced their opinions in favor of seeing the substance legalized.

1. Bernie Sanders -- Senator from Vermont and former presidential candidate

Despite the Drug Enforcement Agency passing on a chance to legalize marijuana this past summer, not all politicians waver on the cannabis debate. Former presidential candidate and current Senator from Vermont Bernie Sanders (I-Vt.) introduced legislation in 2015 that would have ended the federal prohibition of marijuana. Unfortunately for Sanders, his bill had no support.

It's worth noting that a very similar bill was introduced recently by Tom Garrett (R-Va.), but this time it does have some bipartisan cosponsors. While it's unlikely it progresses far in Congress, it's a baby step in the right direction for the marijuana industry.

2. Morgan Freeman -- actor

Of course the man who's played the voice of God on the silver screen not once, but twice, supports the legalization of cannabis. In an interview with The Daily Beast, actor Morgan Freeman had this to say:

Marijuana has many useful uses. I have fibromyalgia pain in this arm [his left arm], and the only thing that offers any relief is marijuana. They're talking about kids who have grand mal seizures, and they've discovered that marijuana eases that down to where these children can have a life.

3. Dalai Lama -- religious leader

Though the Dalai Lama, the Tibetan Buddhist leader, adamantly opposes the use of alcohol and drugs, which includes recreational marijuana, he noted in a 2013 question and answer session, while at an event with former Mexican president Vicente Fox, that the exception for smoking marijuana would be if it had "pharmaceutical virtues."

In plainer English, the Dalai Lama supports medical marijuana in instances where science suggests it may be helpful.

4. Snoop Dogg -- rapper

Fo' shizzle! Not only has the rap artist Snoop Dogg been an outspoken proponent of the cannabis industry for years, but he's also an avid "potrepeneur."

In February of this past year, Snoop Dogg partnered with licensed medical-marijuana producer and retailer Canopy Growth (NYSE:CGC) in Canada to sell three varieties of cannabis under the "Leafs by Snoop" brand, which hit the market in October. With Canada seriously looking at legalizing recreational pot, Snoop's cannabis strains (and Canopy Growth's business in general) could see a serious uptick in demand.

5. Woody Harrelson -- actor

Hollywood is a breeding ground for public influence, and actor Woody Harrelson is hoping to use that influence to advance the uses of marijuana.

According to the New York Daily News, Harrelson is on the advisory board for the National Organization for the Reform of Marijuana Laws, which is better known as NORML. He was also one of the first people to apply to open a medical-marijuana dispensary in Hawaii in 2016. Though Harrelson was denied by the state and other dispensaries were chosen, it didn't douse Harrelson's desire to promote change in the way the federal government views weed.

6. Jesse Ventura -- former Governor of Minnesota

Former wrestling star turned politician Jesse Ventura is arguably the biggest cannabis proponent in the country. His book Jesse Ventura's Marijuana Manifesto clearly suggests that marijuana should be legalized for both medical and recreational purposes.

Ventura has also been a strong opponent of the war on drugs in the U.S, and notes that the legalization movement has had a positive societal impact. He points out that every state that's legalized weed has seen a decline in heroin usage, the opposite of what certain pundits have suggested would happen if weed were legalized.

7. Hugh Hefner -- founder and former CEO of Playboy Enterprises

Given that Hugh Hefner has lived most of his life by pushing media boundaries as the founder and CEO of Playboy Enterprises, it may come as little surprise that he's pushing the envelope for legalizing marijuana in the United States.

Hefner, a noted cannabis user of many, many years, has said "I don't think there's any question that marijuana should be legalized because to not legalize it, we're paying the same price we paid for Prohibition." However, these comments were made in 2010 shortly after California residents voted down a recreational-pot bill in the state. With recreational-weed bill Prop 64 passed as of Nov. 2016 in California, Hefner's outlook is probably a lot greener.

8. Bill Maher -- comedian

Comedian Bill Maher, who may be best known for his HBO talk show Real Time with Bill Maher, is such an avid support of pot that he's even smoked the drug live on air.

Like Harrelson, Maher is on the advisory board of NORML, and he's a key advocate for the national legalization of marijuana. He's said that he smokes marijuana to make his job of writing new material fun. Though Maher has also suggested that legalizing pot is far from the nation's top priority, he's often viewed as a key figure in the legalization movement.

9. Justin Trudeau -- Prime Minister of Canada

The Prime Minister of Canada, Justin Trudeau, could soon become the greatest friend of the legal pot industry. In April, Trudeau introduced legislation that would make recreational marijuana legal in Canada by as early as next year. This would complete an election pledge Trudeau made years back to legalize weed while in office.

Canada's three major medical-marijuana growers obviously love the idea. The aforementioned Canopy Growth, which has 665,000 square feet of growing capacity, along with Aphria (NASDAQOTH: APHQF), which will have 1 million square feet of growing capacity by early next year, and Aurora Cannabis (NYSE:ACB), which is expected to have nearly 900,000 square feet of growing capacity by the end of this year, will all benefit. The Canadian government believes legalizing recreational weed could generate C$5 billion to C$7 billion in annual revenue.

10. Ricky Williams -- former NFL All-Pro running back

Within the sports realm, drug testing keeps most current athletes from being too vocal about marijuana. However, former all-pro NFL running back Ricky Williams is among the most avid supporters from the sports side of the equation.

Aside from just advocating for the legalization of marijuana in the U.S., Williams has also become quite the entrepreneur. He's partnered with a mobile-app company known as Weedmaps, which helps medical marijuana patients locate medical dispensaries, as well as the 420 Games, a series of marijuana-themed races each, yes, 4.20 miles. In San Francisco, Williams also cofounded a cannabis-friendly gym, Power Plant Fitness and Wellness.

11. Jack Nicholson -- actor

And finally, "Here's Johnny!" Well-known actor Jack Nicholson doesn't discuss his views on weed very often, but he was nothing short of blunt in 2011 in a candid conversation with the U.K.'s Daily Mail. Said Nicholson:

I don't tend to say this publicly, but we can see it's [marijuana] a curative thing ... More than 85% of men incarcerated in America are on drug-related offenses. It costs $40,000 a year for every prisoner. If they were really serious about the economy there would be a sensible discussion about legalization.

It remains to be seen if this influential firepower is enough to sway the opinion of lawmakers on Capitol Hill, but having high-profile people in the corner of the marijuana industry certainly can't hurt.