"In 2009-2010, past month marijuana use was reported by 6.8 percent of the U.S. population aged 12 years or older, an increase from 6.4 percent in 2008-2009 (Table C.3). Nine States that were in the top fifth for past month illicit drug use among persons aged 12 or older also were ranked in the top fifth for past month marijuana use: Alaska, Colorado, District of Columbia, Maine, Massachusetts, New Hampshire, Oregon, Rhode Island, and Vermont (Figures 2.1 and 2.9).

"Seven States were ranked in the top fifth for past month marijuana use in age groups 12 to 17, 18 to 25, 26 or older, and 12 or older: Colorado, Maine, Massachusetts, New Hampshire, Oregon, Rhode Island, and Vermont (Figures 2.9 to 2.12). The rate of past month marijuana use in the 12 or older population ranged from 3.1 percent in Utah to 11.8 percent in Alaska (Table B.3). Utah had the lowest rate in all age groups. Between 2008-2009 and 2009-2010, past month marijuana use among persons 12 or older increased in 10 States: Colorado, District of Columbia, Idaho, Illinois, Massachusetts, Michigan, New Mexico, Oklahoma, Texas, and Washington (Table C.3). During the same time period, past month marijuana use increased in one State among 12 to 17 year olds (District of Columbia), eight States among 18 to 25 year olds (Florida, Illinois, Iowa, New Mexico, North Carolina, Oklahoma, Pennsylvania, and Washington), and four States among persons aged 26 or older (District of Columbia, Idaho, Michigan, and Texas). Decreases only occurred in two States: Tennessee, among persons aged 12 or older, and Utah, among youths aged 12 to 17. All four census regions had higher rates of past month marijuana use among persons aged 12 or older in 2009-2010 compared with 2008-2009."

Source

Substance Abuse and Mental Health Services Administration, State Estimates of Substance Use and Mental Disorders from the 2009-2010 National Surveys on Drug Use and Health, NSDUH Series H-43, HHS Publication No. (SMA) 12-4703. Rockville, MD: Substance Abuse and Mental Health Services Administration, 2012.