 In 2005 , Denver became the first major city in the U.S. to vote to make the private possession of less than an ounce of marijuana legal for adults 21 and older . The city voted 53 @.@ 5 percent in favor of the marijuana legalization measure , which , as then @-@ mayor John Hickenlooper pointed out , was without effect , because the city cannot usurp state law , which at that time treated marijuana possession in much the same way as a speeding ticket , with fines of up to $ 100 and no jail time . Denver passed an initiative in the fourth quarter of 2007 requiring the mayor to appoint an 11 @-@ member review panel to monitor the city 's compliance with the 2005 ordinance . In 2012 , Colorado Amendment 64 was signed into law by Governor John Hickenlooper and at the beginning of 2014 Colorado became the first state to allow the sale of marijuana for recreational use . 
