There are currently 51 cannabis companies adopting Colorado highways as a way to advertise and get the public to see their logos on signs along the road, according to the Oregonian. Data from the Adopt a Highway Maintenance Corporation shows that cannabis companies are behind 66% of the sponsored roads in the state. 

The driving reason for companies to go this route is that cannabis advertising is heavily restricted in Colorado and this offers companies a loophole. One of the challenges for Colorado cannabis companies is that in order to advertise on print, TV, or radio, they have to prove their audience is made up mainly of adults aged 21 or older.

Although these road signs aren't technically advertisements as companies can't display messages on them, the signs do show the name and logo of the company sponsoring the highway -- and are often near exits where their stores are located.

Marijuana store sign.

Image source: Getty Images

Colorado continues to be a hot cannabis market 

Marijuana sales in Colorado have been growing since the state became the first in the country to permit recreational sales in 2014. This past year, the state recorded over $1.7 billion in sales, which is more than double the $683 million it generated in its first year. 

One company that looks to get into the Colorado market is Columbia Care (OTC:CCHWF). It announced in November that it would be acquiring The Green Solutions for $140 million, a leading cannabis company in the state. 

Green Thumb Industries (OTC:GTBIF) is another multistate operator with a presence in Colorado where it sells its branded cannabis products including incredibles and Beboe. With more than $161 million in sales over the past 12 months, it's one of the biggest marijuana stocks in the entire country.