Chicago ? Already known as a rural scourge, methamphetamine is becoming a problem in a number of U.S. cities.

Meetings of the 12-step group Crystal Meth Anonymous have increased in Chicago from one night a week a few years ago to five a week. In the Atlanta area, methamphetamine users account for the fastest-growing segment of addicts seeking treatment. Rehabilitation centers there are seeing an uptick in the number of female meth addicts, while officials in Minneapolis-St. Paul say they’re treating an alarming number of meth users younger than 18.

“Most people just think it happens in the farmlands and the prairies or out back behind the barn,” said Carol Falkowski, director of research communications at the Hazelden Foundation in Minnesota. But that’s not the case anymore.

Falkowski found that meth addicts now represent about 10 percent of patients admitted to drug treatment programs in the Twin Cities, compared with 7.5 percent a year ago and about 3 percent in 1998. About a fifth of meth users who sought help in the last year were minors.

She and other experts who track urban drug trends for National Institute on Drug Abuse are meeting this week in Long Beach, Calif., to present their findings. Some have noted a big jump in the use of meth — particularly in its potent crystal form — in the past six months to a year.

“It’s the new major drug threat,” said Jim Hall, director of the Center for the Study and Prevention of Substance Abuse at Nova Southeastern University in Florida. He monitors drug use for the institute in Fort Lauderdale and Miami, where crystal meth is a growing problem.

Partnership for a Drug-Free America launched education campaigns in St. Louis and Phoenix last year to try to combat growing meth problems there. The nonprofit plans similar campaigns in at least four other states in the next year, said spokesman Steve Dnistrian.

“Our fear has been that meth will catch on with a new generation of kids who haven’t heard about it,” he said.

But in some cases, that’s already happening, said Dr. Rob Garofalo at Children’s Memorial Hospital in Chicago.

“It’s the drug that makes me cringe the most,” said Garofalo, who’s come across a growing number of meth users among the patients he treats at the hospital’s clinic for older youth.

At first, he said, these young meth users see the drug as a “brightener” — one that helps them concentrate, stay up for hours and feel in control. In time, however, users become increasingly paranoid and aggressive.

It’s also highly addictive — “such a slippery slope,” Garofalo said. “You can’t just dabble in crystal meth.”