A study just released by the federal Substance Abuse and Mental Health Services Administration shows that marijuana use in the United States has been increasing since states began legalizing medical marijuana. The study indicates that fueled by higher marijuana use, illicit drug use as a whole is up across the country even as the use of most other drugs is down. From Medical News Today: The number of users of marijuana in America rose from 14.4 million in 2007 to 17.4 million in 2010, while the numbers of methamphetamine users aged 12+ years dropped from 731,000 in 2006 to 353,000 in 2010.