Leesburg is the county seat of Loudoun County, Virginia. It was built in 1740 and is named for the Lee family, early leaders of the town and ancestors of Robert E. Lee. In the War of 1812, it was a refuge for important federal documents evacuated from Washington, DC, and in the Civil War, it changed hands several times. The town is situated at the base of Catoctin Mountain and adjacent to the Potomac River, 33 miles (53 km) northwest of Washington, D.C., for which it has largely become a commuter suburb. Its population was 42,616 as of the 2010 census and an estimated 53,727 in 2019. It is Virginia's largest incorporated town within a county (rather than being an independent city).

Middleburg is a town in Loudoun County, Virginia, United States, with a population of 673 as of the 2010 census. It is the southernmost town along Loudoun County's shared border with Fauquier County. Middleburg is known as the "Nation's Horse and Hunt Capital" for its foxhunting, steeplechases, and large estates. The Middleburg Historic District, comprising the 19th-century center of town, is listed on the National Register of Historic Places.

Jefferson County is located in the Shenandoah Valley in the Eastern Panhandle of West Virginia, and is the easternmost county of the U.S. state of West Virginia. As of the 2010 census the population was 53,498. Its county seat is Charles Town. The county was founded in 1801, and today is part of the Washington metropolitan area.

Prince William County is located on the Potomac River in the Commonwealth of Virginia in the United States. As of the 2010 census, the population was 402,002, on July 1, 2019, the population was estimated to be 470,335, making it Virginia's second-most populous county. Its county seat is the independent city of Manassas.A part of Northern Virginia, Prince William County is part of the Washington metropolitan area. In 2019 it had the 20th-highest income of any county in the United States.