Loudoun County continues reign atop richest county list
Forbes bases their county rankings on median household income, which is compiled by the Census Bureau's Small Area Income and Poverty estimates for 2011. The report combines income estimates from the traditional American Community Survey with other administrative records such as tax returns.
According to Forbes' calculations, Loudoun County's median household income is $119,525. Forbes reports the county's population has doubled since 2000, now reaching somewhere in the range of 333,000 people.
Such a population boom is a direct result of business contracting work, plentiful jobs in the public schools system and a presence of such agencies as the Department of Homeland Security, according to Forbes.
Loudoun's development into the nation's capital high-tech corridor has allowed to county to thrive on government spending, which has doubled over the past decade. Loudoun wasn't the only D.C. suburb to make the list as six of the top ten richest counties reside in the D.C. metro area.
Falls Church City comes in at number two with a median income of $117,481. Fairfax County is number four with a median income of $105,409.
Sixth and seventh is Howard County, Md. and Arlington County with median incomes of $99,040 and and $98,060, respectively. Prince William County is 10th with a median income of $93,101.