Places of Virginia

The geography and history of the Commonwealth

Loudoun County, Virginia

Quick answer: Loudoun County is a county in Virginia with its seat at Leesburg. Its estimated population in 2025 was 449,749, up 6.8% since 2020. It covers about 516 square miles of land.
Typecounty
County seatLeesburg
Established1757
Population, 2025 estimate449,749
Population, 2020 estimate422,693
Change 2020–20256.4%
Rank by population in Virginia4 of 133
Church of the Holy Spirit, Leesburg, Virginia
Photo: Dclemens1971 · CC BY 4.0 (license), via Wikimedia Commons, resized

Overview

Virginia has 95 counties, and Loudoun County is one of them.[1] The county seat is Leesburg.[2] The county was established in 1757.[2] The name comes from John Campbell, 4th Earl of Loudoun.[2]

Population of Loudoun County

The U.S. Census Bureau estimated the population of Loudoun County at 449,749 in July 2025, up 6.8% from the April 2020 base of 420,951.[1] That made it 4th of Virginia's 133 counties and independent cities by population. It ranked 21st for growth since 2020.[1]

From 2020 to 2025 the Census Bureau counted about 24,861 births and 9,715 deaths, a natural increase of 15,146.[1] More people moved away to other parts of the United States than moved in. Net domestic migration was -1,943. Moves from abroad added 15,042.[1]

Geography

Loudoun County covers 515.7 square miles of land and 5.6 square miles of water.[3] By land area it ranks 20th of 133 in Virginia.[3] It had about 872 people per square mile in 2025, so it is a mix of towns and countryside. Its geographic center lies near 39.08° N, 77.64° W.[3]

The county borders Clarke County, Fairfax County, Fauquier County and Prince William County in Virginia, as well as land in Maryland and land in West Virginia.[4]

The U.S. Geological Survey place-name database lists 47 named streams, 16 named summits, 30 lakes and reservoirs, 4 gaps and 1 island in the county.[5]

Towns

Loudoun County has 8 incorporated towns. With their estimated 2025 populations, they are: Leesburg (49,917), Purcellville (8,890), Lovettsville (2,708), Round Hill (702), Middleburg (699), Hamilton (608), Hillsboro (112), Herndon (0, part).[6] In Virginia, towns remain part of the county around them, unlike independent cities. "Part" means only the share of the town inside this county.

Frequently asked questions

What is the county seat of Loudoun County?
Leesburg.

What is the population of Loudoun County?
About 449,749 people in 2025, according to the U.S. Census Bureau.

How big is Loudoun County?
About 516 square miles of land, plus 5.6 square miles of water.

References

Official website: www.loudoun.gov

Boundary on the map: Census TIGERweb. See all counties and cities on the map.