Washington County area

Population and density of Washington County

The Census Bureau estimates that 210,802 people lived in Washington County on July 1, 2025. That ranks #343 of 3,222 county equivalents nationally and #18 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 209,331, the population has grown by 1,471 (+0.7%), compared with +0.4% for Pennsylvania as a whole.

With 857 square miles of land, that is 246 people per square mile (95 per km²), placing Washington County #579 nationally for density and #22 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 2.6 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 Washington County

Washington County is divided into 66 municipalities and townships. In Pennsylvania, county subdivisions are local governments, and together they cover all of the county’s land and residents.

The most populous is Peters township, with 23,262 residents (11% of the county). The largest by land is Hanover township, at 47.6 mi², or 5.6% of the county’s land. The county seat, Washington city, has 13,377 residents. Among those with at least 1,000 residents in 2020, North Strabane township grew fastest since then (+10%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Washington County. Land: 2026 Census Gazetteer. How communities are listed.

Metropolitan area

Washington County is a central county of the Pittsburgh, PA Metropolitan Statistical Area. Its 8 county equivalents have 2,421,992 residents on 5,640.3 square miles of land; Washington County accounts for 15.2% of the land and 8.7% of the residents. By combined land it ranks #38 of 393 metropolitan areas, and #28 by population. It belongs to the Pittsburgh-Weirton-Steubenville, PA-OH-WV Combined Statistical Area.

ZIP codes

65 ZIP Code Tabulation Areas have land in Washington County; 56 of them have most of their land inside the county, and the others mainly cover neighboring areas.

1500415012150171501915021150221502615033150381505315054150551505715060150631506715078151021512615129152411530115311153121531315314153171532115322153231532415329153301533115332153331534015342153451534715348153501535815360153611536315365153661536715368153701537615377153781537915412154171541915423154271542915432154341547715483

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 Washington County

Washington County shares a land border with 9 county equivalents, including 4 in West Virginia. It has more land than 8 of them. The largest neighbor is Westmoreland County (1,027.7 mi²) and the smallest is Hancock County (82.6 mi²). Together with its neighbors, Washington County forms a block of 4,999.1 mi² of land, of which it holds 17.1%.

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

Washington County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.2 times as much. Pennsylvania’s county land could hold about 52 areas the size of Washington County.

Another way to picture it: the same land area would fill a square about 29.3 miles (47.1 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 Washington County?

Washington County has more land than 2,251 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 Washington County at #1,068 nationally by total area, 97 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 0.4%, compared with a national county-equivalent median of 1.2% — 0.7 percentage points lower. 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 Washington 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.