Loudoun County is a county located in the Commonwealth of Virginia. In 2014, the population was estimated to be 361,708, making it the third-most populous county in Virginia. Loudoun's county seat is Leesburg. Loudoun County is included in the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area.
, Loudoun County had a median household income of $119,134. Since 2008 the county has been ranked first in the United States in median household income among jurisdictions with a population of 65,000 or more.
Loudoun County was established in 1757 from Fairfax County. The county is named for John Campbell, Fourth Earl of Loudoun and Governor General of Virginia from 1756–59. Western settlement began in the 1720s and 1730s with Quakers, Scots-Irish, Germans and others moving south from Pennsylvania and Maryland and by English and African slaves moving upriver from Tidewater.
By the time of the American Revolution, it was the most populous county in Virginia. In addition, it was rich in agriculture. During the American Revolution, it contributed much of its grain to George Washington’s Continental Army, earning it the nickname “Breadbasket of the Revolution.” During the War of 1812, important Federal documents and government archives were evacuated from Washington and stored at Leesburg for safe keeping. Local tradition holds that these documents were stored at Rokeby House and thus that Leesburg was briefly the capital of the United States.
Early in the American Civil War, the Battle of Balls Bluff took place near Leesburg on October 21, 1861. Future jurist Oliver Wendell Holmes, Jr. was critically wounded in that battle along the Potomac River. During the Gettysburg Campaign in June 1863, Confederate Major General J.E.B. Stuart and Union cavalry clashed in the battles of Aldie, Middleburg, and Upperville. Confederate partisan John S. Mosby based his operations in Loudoun and adjoining Fauquier County (for a more in-depth account of the history of Loudoun County during the Civil War, see Loudoun County in the American Civil War).