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 women 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...