County outline
Where Westmoreland County is located
Area breakdown
Land accounts for 99.2% of Westmoreland County’s measured area and water for 0.8%. Its combined area converts to 2,683.1 square kilometers or approximately 662,996 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 1,027.713 | 2,661.764 | 657,736.3 |
| Water | 8.219 | 21.287 | 5,260.2 |
| Total | 1,035.932 | 2,683.052 | 662,996.5 |
How Westmoreland County compares
By original Census land area, Westmoreland County ranks #8 of 67 in Pennsylvania and #645 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.573 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 2.3% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Westmoreland County
The Census Bureau estimates that 349,324 people lived in Westmoreland County on July 1, 2025. That ranks #216 of 3,222 county equivalents nationally and #11 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 354,607, the population has declined by 5,283 (−1.5%), compared with +0.4% for Pennsylvania as a whole.
With 1,027.7 square miles of land, that is 340 people per square mile (131 per km²), placing Westmoreland County #460 nationally for density and #18 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 1.9 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 354,270 | 353,695 | 351,924 | 351,233 | 350,473 | 349,324 |
| Change | — | −575 | −1,771 | −691 | −760 | −1,149 |
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 Westmoreland County
Westmoreland County is divided into 65 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 Hempfield township, with 41,421 residents (11.9% of the county). The largest by land is Derry township, at 95.6 mi², or 9.3% of the county’s land. The county seat, Greensburg city, has 14,462 residents. Among those with at least 1,000 residents in 2020, Penn township grew fastest since then (+3.4%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Hempfield township | 41,421 | −0.2% | 76.7 | 7.5% |
| North Huntingdon township | 31,697 | −0.5% | 27.3 | 2.7% |
| Unity township | 21,196 | −1.9% | 67.4 | 6.6% |
| Penn township | 20,755 | +3.4% | 30.8 | 3% |
| Murrysville municipality | 20,636 | −1.7% | 36.8 | 3.6% |
| Greensburg cityCounty seat | 14,462 | −3.2% | 4.047 | 0.4% |
| Derry township | 13,360 | −1.9% | 95.6 | 9.3% |
| New Kensington city | 11,759 | −3.2% | 3.949 | 0.4% |
| Lower Burrell city | 11,470 | −2.5% | 11.3 | 1.1% |
| Rostraver township | 11,455 | +0.6% | 32.1 | 3.1% |
| Mount Pleasant township | 9,962 | −1.9% | 55.4 | 5.4% |
| Jeannette city | 8,489 | −3.3% | 2.408 | 0.2% |
| Allegheny township | 8,134 | −2.3% | 31.1 | 3% |
| Latrobe borough | 7,826 | −2.9% | 2.316 | 0.2% |
| East Huntingdon township | 7,587 | −1.5% | 33 | 3.2% |
Show the other 50 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Washington township | 6,789 | −1.3% | 32 |
| Monessen city | 6,657 | −3.2% | 2.887 |
| Salem township | 6,006 | −2.4% | 47.1 |
| Ligonier township | 5,952 | −1.8% | 92.4 |
| Sewickley township | 5,535 | −2.2% | 26.8 |
| South Huntingdon township | 5,303 | −2.3% | 45.4 |
| Vandergrift borough | 4,903 | −3.3% | 1.361 |
| Arnold city | 4,619 | −3.3% | 0.732 |
| Scottdale borough | 4,271 | −3.2% | 1.165 |
| Mount Pleasant borough | 4,108 | −3.3% | 1.001 |
| Irwin borough | 3,759 | −3.1% | 0.838 |
| Manor borough | 3,482 | −2.7% | 1.913 |
| Trafford borough | 3,121 | −3.3% | 1.201 |
| Youngwood borough | 2,878 | −2.9% | 1.918 |
| Delmont borough | 2,630 | +0.7% | 1.056 |
| West Newton borough | 2,569 | −3.3% | 1.037 |
| Derry borough | 2,561 | −3.2% | 0.772 |
| New Stanton borough | 2,338 | +0.9% | 4.006 |
| Donegal township | 2,187 | −0.5% | 49.1 |
| Southwest Greensburg borough | 2,147 | −3.4% | 0.392 |
| Upper Burrell township | 2,114 | −2.4% | 15.1 |
| Bell township | 2,081 | −0.3% | 21.5 |
| South Greensburg borough | 2,073 | −2.4% | 0.707 |
| Loyalhanna township | 2,041 | −2% | 21.6 |
| Fairfield township | 2,034 | −1.1% | 61.4 |
| Cook township | 1,836 | −2.8% | 46.8 |
| North Belle Vernon borough | 1,817 | −3.2% | 0.42 |
| Ligonier borough | 1,462 | −3.2% | 0.504 |
| St. Clair township | 1,302 | −2.9% | 28.6 |
| West Leechburg borough | 1,232 | −2.8% | 0.985 |
| Avonmore borough | 873 | −2.8% | 1.471 |
| Export borough | 865 | −3.1% | 0.403 |
| North Irwin borough | 804 | −2.2% | 0.202 |
| Oklahoma borough | 763 | −3.2% | 0.607 |
| New Florence borough | 648 | −3.3% | 0.328 |
| Penn borough | 610 | +39.9% | 0.157 |
| East Vandergrift borough | 573 | −3.5% | 0.126 |
| Sutersville borough | 543 | −1.8% | 0.272 |
| Hyde Park borough | 491 | −3.3% | 0.24 |
| New Alexandria borough | 479 | −3.2% | 0.847 |
| Bolivar borough | 419 | −3.5% | 0.171 |
| Seward borough | 395 | −3.4% | 0.202 |
| Madison borough | 350 | −3% | 0.436 |
| Smithton borough | 334 | −3.5% | 0.102 |
| Hunker borough | 302 | −2.9% | 0.253 |
| Arona borough | 244 | −3.6% | 0.522 |
| Youngstown borough | 238 | −3.6% | 0.111 |
| Laurel Mountain borough | 142 | −2.7% | 0.129 |
| Adamsburg borough | 136 | −2.9% | 0.28 |
| Donegal borough | 99 | −2.9% | 0.227 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Westmoreland County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Westmoreland 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; Westmoreland County accounts for 18.2% of the land and 14.4% 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.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Allegheny County | 1,225,035 | 730 |
| Westmoreland County | 349,324 | 1,027.7 |
| Washington County | 210,802 | 857 |
| Butler County | 200,169 | 789.5 |
| Beaver County | 166,032 | 434.7 |
| Fayette County | 123,021 | 790.8 |
| Lawrence County | 83,911 | 357.4 |
| Armstrong County | 63,698 | 653.3 |
ZIP codes
89 ZIP Code Tabulation Areas have land in Westmoreland County; 77 of them have most of their land inside the county, and the others mainly cover neighboring areas.
1501215062150681507215083150851508715089151311513715146154481547915501155311560115610156111561215613156151561615617156181561915620156221562315624156251562615627156281562915632156331563415635156361563715638156391564015641156421564415646156471565015655156561565815660156611566215663156651566615668156701567115672156741567515676156771567815679156801568115683156841568715688156891569015691156921569315695156961569715698157171577915923159441595416229
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 Westmoreland County
Westmoreland County shares a land border with 7 county equivalents. It has more land than 6 of them. The largest neighbor is Somerset County (1,075 mi²) and the smallest is Armstrong County (653.3 mi²). Together with its neighbors, Westmoreland County forms a block of 6,649.2 mi² of land, of which it holds 15.5%.
| Bordering county equivalent | Land mi² | Size vs. Westmoreland | Compare |
|---|---|---|---|
| Somerset County | 1,075 | about the same | Compare |
| Washington County | 857 | 1.2× smaller | Compare |
| Indiana County | 827.4 | 1.2× smaller | Compare |
| Fayette County | 790.8 | 1.3× smaller | Compare |
| Allegheny County | 730 | 1.4× smaller | Compare |
| Cambria County | 688 | 1.5× smaller | Compare |
| Armstrong County | 653.3 | 1.6× smaller | Compare |
How big is Westmoreland County compared with U.S. states?
Westmoreland 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 times as much. Pennsylvania’s county land could hold about 44 areas the size of Westmoreland County.
Another way to picture it: the same land area would fill a square about 32.1 miles (51.6 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 Westmoreland County?
Westmoreland County has more land than 2,577 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 Westmoreland County at #738 nationally by total area, 93 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 0.8%, compared with a national county-equivalent median of 1.2% — 0.4 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 Westmoreland County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #644 | Day County, South Dakota | 1,028.5 | Compare |
| #645 | Westmoreland County, Pennsylvania | 1,027.7 | This county |
| #646 | Capitol Planning Region, Connecticut | 1,027.4 | Compare |
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.
Representative coordinates
The Census internal point is 40.311068, -79.466688. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 2,661,763,961 m²; AWATER: 21,288,092 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Westmoreland County?
Westmoreland County, Pennsylvania has 1,027.7 square miles (2,661.8 km²) of land and 8.219 square miles of water, for a total area of 1,035.9 square miles. It ranks #645 of 3,222 U.S. county equivalents by land area.
Is Westmoreland County the largest county in Pennsylvania?
No. Westmoreland County ranks #8 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Westmoreland County?
Westmoreland County shares a land border with Allegheny County, Fayette County, Indiana County, Somerset County, Armstrong County, Cambria County, and Washington County.
What is the population of Westmoreland County?
The Census Bureau estimates Westmoreland County had 349,324 residents on July 1, 2025, ranking #216 of 3,222 county equivalents. That is 340 people per square mile of land.
What is the county seat of Westmoreland County?
The county seat of Westmoreland County is Greensburg.
What cities and towns are in Westmoreland County?
Westmoreland County has 65 county subdivisions (cities, towns and townships). The most populous five are Hempfield township, North Huntingdon township, Unity township, Penn township, and Murrysville municipality.
Is Westmoreland County part of a metropolitan area?
Yes. It is a central county of the Pittsburgh, PA Metropolitan Statistical Area, which has 8 county equivalents and 2,421,992 residents.
How many ZIP codes are in Westmoreland County?
89 ZIP Code Tabulation Areas have land in Westmoreland County, and 77 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Westmoreland County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1 times as much land.
How many acres of land are in Westmoreland County?
The land measurement converts to approximately 657,736 acres. Including water, total area is approximately 662,996 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.