Loudoun County area

Population and density of Loudoun County

The Census Bureau estimates that 449,749 people lived in Loudoun County on July 1, 2025. That ranks #167 of 3,222 county equivalents nationally and #4 of 133 in Virginia. Since the April 1, 2020 estimates base of 420,951, the population has grown by 28,798 (+6.8%), compared with +2.9% for Virginia as a whole.

With 515.7 square miles of land, that is 872 people per square mile (337 per km²), placing Loudoun County #209 nationally for density and #38 in Virginia. The median county equivalent has 47 people per square mile; the Virginia median is 109. Put another way, there are about 0.734 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Loudoun County

8 incorporated places lie at least partly in Loudoun County. Together they are home to 63,636 people (14.1%); the other 386,113 (85.9%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Leesburg town, with 49,917 residents in the county. Among places with at least 1,000 residents in 2020, Leesburg town grew fastest since then (+3.3%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Loudoun County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Loudoun County is a central county of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area, in the Arlington-Alexandria-Reston, VA-WV metropolitan division. Its 23 county equivalents have 6,465,724 residents on 6,033.7 square miles of land; Loudoun County accounts for 8.5% of the land and 7% of the residents. By combined land it ranks #35 of 393 metropolitan areas, and #7 by population. It belongs to the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area.

ZIP codes

21 ZIP Code Tabulation Areas have land in Loudoun County; 17 of them have most of their land inside the county, and the others mainly cover neighboring areas.

201052011720120201292013020132201352014120147201482015220158201642016520166201752017620180201842019722066

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Loudoun County

Loudoun County shares a land border with 8 county equivalents, including 4 in Maryland and West Virginia. It has more land than 6 of them. The largest neighbor is Frederick County (660.7 mi²) and the smallest is Clarke County (176 mi²). Together with its neighbors, Loudoun County forms a block of 3,886.9 mi² of land, of which it holds 13.3%.

How big is Loudoun County compared with U.S. states?

Loudoun County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2 times as much. Virginia’s county land could hold about 77 areas the size of Loudoun County.

Another way to picture it: the same land area would fill a square about 22.7 miles (36.5 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Loudoun County?

Loudoun County has more land than 1,199 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Loudoun County at #2,100 nationally by total area, 77 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 1.1%, compared with a national county-equivalent median of 1.2%. The two percentages are within 0.1 percentage points of each other. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Loudoun County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.