If you're investing for the long term, it can be beneficial to stake out positions in some high-growth industries before they take off. One opportunity that investors are likely overlooking right now is in cannabis. The big drawback is that while cannabis products are legal in dozens of states, cannabis remains banned on a federal level.

It's unclear how long investors may need to wait until that changes and legalization takes place. But there's one impressive and surprising stat that should grab the attention of lawmakers and investors, and it suggests that changes could come sooner rather than later.

More common than smoking tobacco

Data from Gallup polls last month confirmed what many people in the country already know: marijuana is rising in popularity. According to one poll, 16% of Americans admitted to smoking marijuana within the past week. By comparison, only 11% of people claimed to have smoked tobacco cigarettes over the same period. That's the first time that Gallup data has shown that marijuana is more widely used than tobacco.

It's an important milestone because Gallup is a top analytics company and its polls are known worldwide and are often used to gauge trends. The data could incentivize companies to transition more toward the cannabis industry, and perhaps away from tobacco.

Companies have already begun to pivot

People who smoke tobacco or marijuana are often looking for similar relaxing experiences. Tobacco, however, has been linked to cancer and all sorts of health problems. Companies like Altria (MO 1.91%), which makes Marlboro cigarettes, have been focusing on harm-reduction products in order to better meet customers' needs.

Cannabis can also be a potential solution. In 2018, Altria invested $1.8 billion in cannabis producer Cronos Group, or a 45% stake in the business. British American Tobacco has also invested in the industry, announcing earlier this year that it now owns 19.5% of cannabis producer OrganiGram. 

And it's not just tobacco companies that are paying more attention to cannabis. It has now been four years since beer maker Constellation Brands invested $4 billion in pot giant Canopy Growth. Cannabis-based beverages have the potential to be an attractive alternative for the alcohol industry as they don't contain as many calories and they don't cause dreadful hangovers.

The opportunities are only going to grow

According to analysts from Facts and Factors, the global legal marijuana market will be worth $97 billion by 2026, growing at a compound annual rate of 28% over that time. More countries are looking at legalizing marijuana, with Germany potentially being among the most notable, which will open more doors for the industry.

While the Horizons Marijuana Life Sciences ETF is down 58% over the past year and has performed much worse than the S&P 500 over that stretch (it has declined just 8%), that trend could change drastically in the years ahead if legalization continues to make progress in the U.S. and around the world. Knowing that there is a growing number of users potentially switching to pot could be what gets more companies to invest in the industry.

And as more attention is put on cannabis, the more likely it is that presidential candidates include legalization in their plans or as part of their campaign promises. Although it can be unnerving to invest in crashing pot stocks right now, it could pay off significantly in the long run.