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Loudoun County, Virginia facts for kids

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Loudoun County
Loudoun County
The Loudoun County Courthouse at Leesburg in May 2010
The Loudoun County Courthouse at Leesburg in May 2010
Flag of Loudoun County
Official seal of Loudoun County
"I Byde My Time"
Map of Virginia highlighting Loudoun County
Location within the U.S. state of Virginia
Map of the United States highlighting Virginia
Virginia's location within the U.S.
Country  United States
State  Virginia
Founded 1757
Named for John Campbell, 4th Earl of Loudoun
Seat Leesburg
Largest town Leesburg
 • Total 521 sq mi (1,350 km2)
 • Land 516 sq mi (1,340 km2)
 • Water 6 sq mi (20 km2)  1.1%%
 • Estimate 
 • Density 721/sq mi (278/km2)
Time zone UTC−5 (Eastern)
 • Summer (DST) UTC−4 (EDT)
Congressional district 10th

Loudoun County ( LOWD-ən) is a county in the Commonwealth of Virginia. In 2015, the population was estimated at 375,629, making it Virginia's third-most populous county. Loudoun's county seat is Leesburg. Loudoun County is part of the Washington–Arlington–Alexandria, DC–VA–MD–WV Metropolitan Statistical Area.

As of 2012, Loudoun County had a median household income of $117,876. 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.

William and Sarah Nettle House Waterford Loudoun County Virginia
William and Sarah Nettle House, Waterford, Loudoun County

By the time of the American Revolution, it was Virginia's most populous county. It was also rich in agriculture, and the county's contributions of grain to George Washington's Continental Army, earned 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. Local tradition holds that these documents were stored at Rokeby House, making Leesburg briefly the capital of the United States.

U.S. President James Monroe treated Oak Hill Plantation as a primary residence from 1823 until his death on July 4, 1831. The Loudoun County coat of arms and flag, granted by the English College of Arms, memorialize the special relationship between Britain and the United States that developed through his Monroe Doctrine.

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).

In 1962, Washington Dulles International Airport was built in southeastern Loudoun County in Sterling. Since then, Loudoun County has experienced a high-tech boom and rapid growth. Accordingly, many have moved to eastern Loudoun and become residents of planned communities such as Sterling Park, Sugarland Run, Cascades, and Ashburn Farms, making that section a veritable part of the Washington suburbs. Others have moved to the county seat or to the small towns and rural communities of the Loudoun Valley.


According to the U.S. Census Bureau, Loudoun County has a total area of 521 square miles (1,350 km2), of which 516 square miles (1,340 km2) is land and 6 square miles (16 km2) (1.1%) is water. It is bounded on the north by the Potomac River; across the river are Frederick, Washington and Montgomery counties in Maryland; it is bounded on the south by Prince William and Fauquier counties, on the west by watershed of the Blue Ridge Mountain across which are Jefferson County, West Virginia and Clarke County, and on the east by Fairfax County. The Bull Run Mountains and Catoctin Mountain bisect the county. To the west of the range is the Loudoun Valley. Bisecting the Loudoun Valley from Hillsboro to the Potomac River is Short Hill Mountain.

Street addresses

Block numbers in the unincorporated areas of Loudoun County, with the exception of older Sterling Park and the community of CountrySide, are assigned in the following manner: on north-south streets, block numbers increase from north to south and range from 10000 to 27000; on east-west streets, block numbers increase from west to east and range from 30000 to 48000.

Adjacent counties

National protected area


Historical population
Census Pop.
1790 18,962
1800 20,523 8.2%
1810 21,338 4.0%
1820 22,702 6.4%
1830 21,939 −3.4%
1840 20,431 −6.9%
1850 22,079 8.1%
1860 21,774 −1.4%
1870 20,929 −3.9%
1880 23,634 12.9%
1890 23,274 −1.5%
1900 21,948 −5.7%
1910 21,167 −3.6%
1920 20,577 −2.8%
1930 19,852 −3.5%
1940 20,291 2.2%
1950 21,147 4.2%
1960 24,549 16.1%
1970 37,150 51.3%
1980 57,427 54.6%
1990 86,129 50.0%
2000 169,599 96.9%
2010 312,311 84.1%
Est. 2015 375,629 20.3%
U.S. Decennial Census
1790-1960 1900-1990

As of the census of 2010, there were 312,311 people, 104,583 households, and 80,494 families residing in the county. The population density was 606 people per square mile (234/km²). There were 109,442 housing units at an average density of 212 per square mile (82/km²). The racial makeup of the county was:

  • 68.7% White
  • 7.3% African American
  • 14.7% Asian
  • 0.3% Native American
  • 0.1% Pacific Islander
  • 4.9% of some other race
  • 4.0% of two or more races
  • 12.4% of the population were Hispanic or Latino of any race (3.4% Salvadorian, 1.8% Mexican, 1.3% Peruvian, 0.9% Puerto Rican, 0.6% Honduran, 0.6% Bolivian, 0.5% Guatemalan, 0.5% Colombian)

According to the 2010 census, 10.5% of residents reported being of German ancestry, while 9.1% reported Irish, 7.7% English, 5.4% Italian and 5.2% American ancestry.

As of 2000 there were 59,900 households out of which 43.10% had children under the age of 18 living with them, 64.30% were married couples living together, 7.80% had a female householder with no husband present, and 24.80% were non-families. 18.40% of all households were made up of individuals and 3.70% had someone living alone who was 65 years of age or older. The average household size was 2.82 and the average family size was 3.24.

In the county, the population was spread out with 29.80% under the age of 18, 5.70% from 18 to 24, 38.90% from 25 to 44, 20.00% from 45 to 64, and 5.60% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 97.80 males. For every 100 females age 18 and over, there were 95.50 males.

In 2011, Census survey data concluded that Loudoun County had the highest median income in the country at $119,134.

From 1980 to 2014, deaths from cancer in Loudoun County decreased by 46 percent, the largest such decrease of any county in the United States.



Loudoun County has two airports: the Washington Dulles International and Leesburg Executive.


Loudoun County operates its own bus public transit system, known as Loudoun County Commuter Bus.


The Silver Line of the Washington Metro, will extend into Loudoun County. The planned extension will include stations at the Dulles International Airport, and two stations in Ashburn, Virginia.

Major highways

  • US 15.svg U.S. Route 15
  • US 50.svg U.S. Route 50
  • US 340.svgU.S. Route 340
  • Virginia 7.svg State Route 7
  • Virginia 9.svg State Route 9
  • Virginia 28.svg State Route 28
  • Virginia 267.svg State Route 267 (Dulles Greenway)
  • Circle sign 606.svgCircle sign 607.svgCircle sign 772.svgCircle sign 1950.svg Loudoun County Parkway



Census-designated places

Other unincorporated communities

Images for kids

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