About 13 percent of San Francisco residents told federal researchers they used some type of illicit drug in the past month, the highest reported drug-use rate in the country, USA Today reported Jan. 8.

The data reported by the Substance Abuse and Mental Health Services Administration (SAMHSA) included use of all illicit drugs, including marijuana, cocaine and heroin. Nationally, 8.1 percent of Americans say they are monthly users of illicit drugs. Seattle, Detroit, Philadelphia, and Boston also reported higher-than-average rates of monthly drug use.

"The fact that [California] state law allows the use of medical marijuana and that we have a population with a high rate of AIDS that might need to use medical marijuana may contribute to the rates," said Alice Gleghorn, deputy director of community behavioral health services for the San Francisco Department of Public Health. "We do have a cultural regional norm with regard to medical-marijuana use."

Marijuana also is grown extensively in the Bay Area. "Where marijuana is very accessible, you're going to get higher use," Gleghorn noted. Also, prevention efforts in the city are aimed at heroin, methamphetamine and cocaine, not marijuana.

Conversely, San Francisco has one of the lowest tobacco smoking rates in the country, SAMHSA reported.

The report also found that Chicago and Houston had the highest rates of binge drinking nationwide. SAMHSA officials said the data will help local prevention officials target their resources appropriately.