Fairfax County is a county in Northern Virginia, in the United States. As of April 2008^[update], the estimated population of the county is 1,015,302,^[1] making it by far the most populous jurisdiction in the Commonwealth of Virginia, and the most populous jurisdiction in the Washington Metropolitan Area. Fairfax was the first county to reach a six-figure median household income, and has the second-highest median household income of any jurisdiction in the United States after neighboring Loudoun County.^[2]

http://en.wikipedia.org/wiki/Fairfax_County,_Virginia