Loudoun County, Virginia
Loudoun County () is in the northern part of the Commonwealth of Virginia in the United States. In 2020, the census returned a population of 420,959, making it Virginia's third-most populous county. The county seat is Leesburg. Loudoun County is part of the Washington–Arlington–Alexandria, DC–VA–MD–WV Metropolitan Statistical Area. As of 2023, Loudoun County had a median household income of $156,821, the highest of any county or county equivalent in the nation.