Thousands stood in line on Wednesday to be the first to legally purchase recreational marijuana in the state of Colorado.

At least 37 stores across Colorado were fully licensed and opened to sell marijuana to anyone 21 or over for any purpose on Wednesday, the Denver Post reported. Sales started at 8 a.m.

Across the state, thousands cheerfully braved bitter cold weather and stood in line for hours to legally buy marijuana. Besides the money, all they needed was identification.

The first customer at 3D Cannabis Center in Denver was 32-year-old Sean Azzariti, an Iraq war veteran who campaigned for marijuana legalization and said he uses cannabis to alleviate symptoms of post-traumatic stress disorder.

Azzariti bought an eighth of an ounce of the marijuana strain Bubba Kush and a package of marijuana-infused candy truffles for a total of $59.74, including $10.46 in tax.

Those against the legalization of marijuana are afraid recreational sales will lead to an increase of marijuana addiction in adults and children.

Marijuana sales remain illegal under federal law, but under Colorado law state residents can purchase up to an ounce of marijuana and out-of-state residents can buy a quarter-ounce.

The state of Washington will launch a marijuana industry similar to Colorado's later this year.

The U.S. Department of Justice decided not to block legalization in either state, so long as the states implement strict regulations on the stores.