As far as the cities and counties with the richest number of people here are the 2004 ranks: Rank City Median household income, 2004 1 San Jose, CA $71,765 2 Anchorage, AK $61,565 3 San Francisco, CA $60,031 4 Virginia Beach, VA $55,781 5 San Diego, CA $51,382 6 Anaheim, CA $49,622 7 Raleigh, NC $47,878 8 Seattle, WA $46,650 9 Washington, DC $46,574 10 Honolulu, HI $46,500 11 Oakland, CA $46,190 12 Charlotte, NC $46,082 13 Boston, MA $45,892 14 Arlington, TX $45,712 15 Austin, TX $45,508 16 Colorado Springs, CO $45,388 17 Riverside, CA $44,866 18 Las Vegas, NV $44,737 19 Aurora, CO $44,480 20 Minneapolis, MN $44,11 As for the counties (more specific): Rank City Median household income, 2004 1 Fairfax County, VA $83,975 2 Somerset County, NJ $84,892 3 Morris County, NJ $83,583 4 Montgomery County, MD $82,971 5 Howard County, MD $82,065 6 Nassau County, NY $78,762 7 Prince William County, VA $77,678 8 Monmouth County, NJ $77,223 9 Rockland County, NY $75,306 10 Santa Clara County, CA $74,509 11 Fairfield County, CT $73,110 12 Chester County, PA $72,288 13 Suffolk County, NY $71,956 14 McHenry County, IL $71,153 15 Bergen County, NJ $70,957 16 Norfolk County, MA $70,903 17 Lake County, IL $70,347 18 Middlesex County, NJ $70,344 19 DuPage County, IL $70,174 20 Westchester County, NY $70,095 However, these are only for populations OVER 250,000 PEOPLE. Here is the source: http://money.cnn.com/2005/08/30/pf/city_county_rankings/index.htm