The five richest counties in the United States when measured by median household income are all suburbs of Washington, D.C., according to the American Community Survey data released today by the Census Bureau. According to the American Community Survey's new five-year estimates (2012-2016), the five richest counties in the country are: Loudoun County, Va., where the median household income was $125,672; Falls Church City, Va., where it was $115,244; Fairfax County, Va., where it was $114,329; Howard County, Md., where it was $113,800; and Arlington County, Va., where it was $108,706.