Arlington County, Virginia

Arlington County is a county in Virginia, United States, directly across the Potomac River from Washington, D.C. It had a population of 238,643 at the 2020 census, an estimated 243,931 by 2025, and covers 25.8 square miles (67 km2) centred near 38°52′49″N 77°06′30″W.

Courthouse is the county seat; its postal code is 22201. Arlington has no incorporated cities or towns — the entire county is run as a single, self-governing jurisdiction, and Virginia has no civil townships. Its roughly 60 named neighborhoods function as the county’s informal urban villages rather than municipalities. Arlington runs on Eastern time, and its FIPS code is 51013.

Towns & Villages in Arlington County

Arlington is often described as a “city without a charter”: it is the smallest self-governing county in the United States by land area, and every part of it — from the high-rise Rosslyn–Ballston corridor to quiet residential streets near Marymount University — is unincorporated county territory. There are no separate towns, cities or CDPs to list. Instead, the table below covers the county’s major recognized neighborhoods and commercial districts. The Census Bureau tabulates population for the county as a whole (as “Arlington CDP”, coextensive with the county boundary), not for individual neighborhoods, so per-neighborhood population figures are not published and are marked — below rather than estimated.

Two confusable pairs are worth flagging. This Arlington shares its name with Arlington, Texas, and Arlington, Massachusetts — both separate, independently incorporated cities and towns with no connection to Arlington County, Virginia. Locally, the neighborhood of East Falls Church sits inside Arlington County, while the adjoining City of Falls Church just to its west is a separate, independent Virginia city with its own government — the two are not the same place despite the shared name and shared Metro station.

ZIP Codes

USPS/zip-codes.com data lists 28 ZIP codes touching Arlington County: 11 standard delivery codes, 4 PO-box-only codes and 13 unique codes tied to specific buildings or federal tenants, with a combined standard-delivery population of roughly 236,700.

• 22201 — Arlington (serves Courthouse, Clarendon, Lyon Village, Lyon Park and Colonial Village)
• 22202 — Arlington (serves Crystal City, Pentagon City, Aurora Highlands and Arlington Ridge)
• 22203 — Arlington (serves Virginia Square and Ballston)
• 22204 — Arlington (serves the Columbia Pike corridor, Barcroft, Douglas Park, Alcova Heights and Green Valley/Nauck)
• 22205 — Arlington (serves Westover, Bluemont, Dominion Hills and Arlington Forest)
• 22206 — Arlington (serves Shirlington and Fairlington)
• 22207 — Arlington (serves Cherrydale, Yorktown and Country Club Hills, North Arlington)
• 22209 — Arlington (serves Rosslyn)
• 22211 — Fort Myer (Joint Base Myer–Henderson Hall, a military installation with its own ZIP)
• 22213 — Arlington (serves East Falls Church and the Bluemont Junction area)
• 20301 — The Pentagon (a dedicated ZIP code for the Department of Defense headquarters)

The remaining unique and PO-box codes (22210, 22212, 22214–22217, 22219, 22225–22227, 22230, 22240–22246) carry no residential population — they are box-holder or agency-specific codes rather than delivery areas for named places.

Geography

Arlington sits on the fall line between the Piedmont and the Coastal Plain, on the southwestern bank of the Potomac River directly opposite Washington, D.C. Of its 26.0 square miles, 25.8 square miles are land and 0.2 square miles (0.8 percent) are water. The Potomac forms the county’s entire northeastern boundary; Four Mile Run, a Potomac tributary, forms most of the southern boundary with the City of Alexandria. Elevations range from sea level along the Potomac shoreline to roughly 360 feet near Ballston, the county’s highest ground.

Arlington borders Fairfax County to the west and southwest, the independent City of Alexandria to the south, and the independent City of Falls Church — a small enclave entirely surrounded by Arlington and Fairfax — to the west. Washington, D.C. lies directly across the Potomac to the northeast; the river, not a land line, separates the two.

Demographics

Arlington counted 238,643 residents at the 2020 census, up from 207,627 in 2010, and Census Bureau population-estimate figures put the county at roughly 243,931 by 2025. Population density runs about 9,375 people per square mile, among the highest of any county in Virginia. The largest concentrations of residents and jobs sit in the Rosslyn–Ballston corridor (Rosslyn, Courthouse, Clarendon, Virginia Square, Ballston) and the Jefferson Davis corridor (Crystal City, Pentagon City), both built around Metrorail stations. Median household income was $142,114 as of 2024, well above Virginia’s statewide median of $93,170.

Economy & Local Life

Arlington’s economy runs on the federal government and the professional services that surround it. Professional, scientific and technical services employ about 38,500 county workers, public administration another 24,150, and educational services roughly 12,500, according to Census-derived Data USA figures. The Pentagon, the U.S. Department of Defense’s headquarters, sits in the county’s Pentagon City/Arlington Ridge area and is itself one of the world’s largest office buildings. Amazon’s HQ2 East Coast headquarters occupies part of Crystal City and Pentagon City, rebranded “National Landing.” Marymount University has its main campus in North Arlington. The Rosslyn–Ballston and Crystal City corridors carry the county’s dense office, retail and high-rise residential development, built deliberately around five Metrorail stations since the 1970s. The county’s largest recurring public event is the Arlington County Fair, held each August at the Thomas Jefferson Community Center.

History

The area was originally home to the Nacotchtank people before European settlement. What is now Arlington County was organized in 1801 as Alexandria County, part of the land Virginia ceded to form the new federal District of Columbia. Congress returned the territory to Virginia in 1847, a process known as retrocession, after residents petitioned that being under federal rather than state governance denied them representation. The county kept the name Alexandria County until 1920, when it was renamed Arlington County to avoid confusion with the separate, independently incorporated City of Alexandria next door — taking its new name from Arlington House, the Custis-Lee family estate that overlooks the Potomac.

The federal government confiscated that estate during the Civil War over an unpaid tax bill and established Arlington National Cemetery on the grounds on May 13, 1864; the cemetery now holds roughly 400,000 graves across 639 acres. Freedman’s Village, a settlement for formerly enslaved people, operated on part of the same land from 1863 to 1887. The Pentagon was built in the county during World War II, completed in 1943. In 1959 Arlington became the first Virginia county to desegregate its public schools, and in 1960 the first to desegregate its businesses under court order.

Getting There

Interstate 395 runs north–south through the county past the Pentagon, Crystal City and Shirlington; Interstate 66 crosses the northern part of the county on its way into Washington, D.C. U.S. Route 50 (Arlington Boulevard) and the George Washington Memorial Parkway, which follows the Potomac shoreline, are the other principal through routes.

• Washington, D.C. — about 1 mile east, across the Potomac via the Key Bridge or Arlington Memorial Bridge
• Alexandria — about 4 miles south
• Falls Church — adjoins the county directly to the west
• Fairfax — about 12 miles west

Ronald Reagan Washington National Airport (DCA) is not merely nearby — it sits inside Arlington County itself, between Crystal City and the Potomac. The nearest Amtrak station is Washington Union Station, about 4 miles northeast across the river; Virginia Railway Express commuter trains also stop within the county at the Crystal City station.

Frequently Asked Questions

Where is Arlington County, Virginia?
It sits in Northern Virginia on the southwestern bank of the Potomac River, directly across from Washington, D.C.

What is the population of Arlington County?
238,643 at the 2020 census, with an estimated population of about 243,931 by 2025.

How big is Arlington County?
25.8 square miles (67 km2) of land, plus 0.2 square miles of water — making it the smallest self-governing county in the United States by land area.

What is the county seat of Arlington County?
Courthouse is the county seat, home to the county government complex; its ZIP code is 22201.

Does Arlington County have any incorporated towns or cities?
No. The county has zero incorporated municipalities; it operates as a single self-governing jurisdiction with roughly 60 informally named neighborhoods.

What ZIP codes cover Arlington County?
Mainly 22201 through 22209, plus 22211 (Fort Myer), 22213 (East Falls Church) and 20301 (the Pentagon).

Is this Arlington the same place as Arlington, Texas?
No. Arlington County, Virginia, is a distinct, unrelated jurisdiction from Arlington, Texas, and Arlington, Massachusetts, which are separately incorporated cities and towns.

More counties in this state: Towns and villages in Virginia.