16:57 02 January 2014
While January 1st was New Year's Day for most, in Colorado it was dubbed Green Wednesday after as many as 30 stores began legally selling cannabis.
The state voted to legalise the use and possession of the drug for people aged 21 and over. Washington is set to follow suit next year.
While Colorado and Washington are among 20 states who allow the drug for medical purposes, cannabis is still deemed illegal under federal laws.
In Colorado, the drug will be sold and taxed in a similar method to alcohol. The Denver Post reported that the first $40m raised through selling the drug will build a new school.
136 stores in the state were granted a license to sell the drug with at least 30 starting trading on the first day of the year. As a result, extra security was brought in.
Kevin Sabet of Smart Approaches to Marijuana described the move as "the worst of both worlds", citing that "there will still need to be a black market to serve people who are ineligible to buy on a legal market, especially kids."
Rachel Gillette of the Colorado branch of the National Organization for the Reform of Marijuana Laws was quoted by the BBC with a more positive outlook. She praised Colorado for "finding an exit strategy for the failed drug war and I hope other states will follow our lead".