- Falls Church City, VA ($121,250)
- Loudoun County, VA ($118,934)
- Los Alamos County, NM ($112,115)
- Howard County, MD ($108,234)
- Fairfax County, VA ($106,690)
- Hunterdon County, NJ ($103,301)
- Arlington County, VA ($99,255)
- Douglas County, CO ($98,426)
- Stafford County, VA ($95,927)
- Somerset County, NJ ($95,574)
Six of the top 10 counties surrounds the nation's capital in Washington, D.C., home to a variety of federal agencies, departments, and bedroom communities for government workers. The less obvious member of the list is Los Alamos County in New Mexico, home to the Los Alamos National Laboratory.
When you think of rich counties, which come to mind? Parts of Silicon Valley are quite affluent, yet Santa Clara County, CA is number 17 on the list. Marin County, CA is number 19.
You can download the Census Bureau's data spreadsheet here. The spreadsheet also shows the poorest U.S. counties based on median household income.