a factor with levels Akron OH Albuquerque NM Anaheim CA Atlanta GA Baltimore MD Baton Rouge LA Birmingham AL Boston MA Bradenton FL Buffalo, NY Charleston, SC Chicago, IL Cincinnati, OH Cleveland, OH Columbia, SC Columbus, OH Corpus Christi, TX Dallas, TX Daytona Beach, FL Denver, CO Des Moines, IA Detroit, MI El Paso, TX Grand Rapids, MI Hartford, CT Honolulu, HI Houston, TX Indianapolis, IN Jacksonville, FL Kansas City, MO Knoxville, TN Las Vegas, NV Los Angeles, CA Louisville, KY Madison, WI Memphis, TN Miami, FL Milwaukee, WI Minneapolis, MN Mobile, AL Nashville, TN New Haven, CT New Orleans, LA New York, NY Oklahoma City, OK Omaha, NE Orlando, FL Philadelphia, PA Phoenix, AZ Pittsburgh, PA Portland, OR Providence, RI Sacramento, CA Salt Lake City, Ut San Antonio, TX San Diego, CA San Francisco, CA Seattle, WA Spokane, WA St Louis, MO Syracuse,NY Tampa, FL Toledo, OH Tulsa, OK Washington, DC