County outline
Where Allegheny County is located
Area breakdown
Land accounts for 98.1% of Allegheny County’s measured area and water for 1.9%. Its combined area converts to 1,927.6 square kilometers or approximately 476,324 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 729.952 | 1,890.567 | 467,169.3 |
| Water | 14.304 | 37.047 | 9,154.6 |
| Total | 744.256 | 1,927.614 | 476,323.8 |
How Allegheny County compares
By original Census land area, Allegheny County ranks #29 of 67 in Pennsylvania and #1215 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.117 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 1.6% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Allegheny County
The Census Bureau estimates that 1,225,035 people lived in Allegheny County on July 1, 2025. That ranks #39 of 3,222 county equivalents nationally and #2 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 1,250,581, the population has declined by 25,546 (−2%), compared with +0.4% for Pennsylvania as a whole.
With 730 square miles of land, that is 1,678 people per square mile (648 per km²), placing Allegheny County #99 nationally for density and #4 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 0.381 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 1,249,585 | 1,245,335 | 1,233,325 | 1,228,911 | 1,227,174 | 1,225,035 |
| Change | — | −4,250 | −12,010 | −4,414 | −1,737 | −2,139 |
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 Allegheny County
Allegheny County is divided into 130 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 Pittsburgh city, with 307,632 residents (25.1% of the county), and it is also the largest by land at 55.4 mi². Among those with at least 1,000 residents in 2020, Findlay township grew fastest since then (+18.3%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Pittsburgh cityCounty seat | 307,632 | +1.5% | 55.4 | 7.6% |
| Penn Hills municipality | 39,452 | −3.8% | 19.1 | 2.6% |
| Mount Lebanon municipality | 32,552 | −4.4% | 6.078 | 0.8% |
| Ross township | 32,218 | −4% | 14.5 | 2% |
| Bethel Park municipality | 32,074 | −4.5% | 11.7 | 1.6% |
| McCandless township | 28,439 | −4.3% | 16.5 | 2.3% |
| Monroeville municipality | 27,685 | −3.3% | 19.7 | 2.7% |
| Shaler township | 26,833 | −4.6% | 11.1 | 1.5% |
| Moon township | 26,756 | −1.8% | 23.9 | 3.3% |
| Plum borough | 26,225 | −3.4% | 28.6 | 3.9% |
| Baldwin borough | 20,516 | −4.7% | 5.771 | 0.8% |
| Upper St. Clair township | 20,466 | −3.3% | 9.816 | 1.3% |
| West Mifflin borough | 18,707 | −4.5% | 14.2 | 1.9% |
| South Fayette township | 18,648 | +1.6% | 20.3 | 2.8% |
| Hampton township | 17,808 | −3.6% | 16.2 | 2.2% |
Show the other 115 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| McKeesport city | 16,907 | −4.6% | 5.049 |
| Scott township | 16,838 | −4.5% | 3.894 |
| North Fayette township | 16,017 | −1% | 25.2 |
| Robinson township | 15,735 | +1.5% | 15.2 |
| Pine township | 15,475 | +5.3% | 17 |
| Franklin Park borough | 14,978 | −3.3% | 13.5 |
| Whitehall borough | 14,521 | −3.5% | 3.325 |
| South Park township | 13,613 | −0.7% | 9.337 |
| Wilkinsburg borough | 13,602 | −4.9% | 2.253 |
| Elizabeth township | 12,399 | −4.5% | 22.8 |
| Jefferson Hills borough | 12,357 | −0.5% | 16.6 |
| West Deer township | 12,301 | +0.4% | 28.9 |
| Richland township | 11,840 | −0.9% | 14.6 |
| Marshall township | 10,499 | +4.1% | 15.4 |
| Munhall borough | 10,253 | −4.9% | 2.293 |
| Harrison township | 9,688 | −4.8% | 7.387 |
| Brentwood borough | 9,597 | −4.9% | 1.449 |
| North Versailles township | 9,587 | −4.8% | 8.001 |
| Collier township | 9,103 | +1.9% | 13.6 |
| O'Hara township | 8,909 | −4% | 7.014 |
| Kennedy township | 8,419 | −3.3% | 5.484 |
| Pleasant Hills borough | 8,212 | −3.2% | 2.775 |
| Swissvale borough | 8,197 | −5% | 1.206 |
| Castle Shannon borough | 8,006 | −2.9% | 1.598 |
| Bellevue borough | 7,888 | −4.9% | 1.01 |
| Dormont borough | 7,816 | −5% | 0.76 |
| Carnegie borough | 7,777 | −4.5% | 1.621 |
| Findlay township | 7,541 | +18.3% | 32.3 |
| Indiana township | 7,420 | +2.3% | 17.6 |
| White Oak borough | 7,286 | −4.7% | 6.619 |
| Ohio township | 7,268 | +1.4% | 6.852 |
| Oakmont borough | 6,576 | −2.7% | 1.584 |
| West View borough | 6,355 | −4.9% | 1.01 |
| Stowe township | 6,119 | −4.9% | 1.982 |
| Forest Hills borough | 6,116 | −4.9% | 1.565 |
| Wilkins township | 6,044 | −4.8% | 2.741 |
| Clairton municipality | 5,876 | −4.9% | 2.769 |
| Crafton borough | 5,790 | −5% | 1.142 |
| McKees Rocks borough | 5,624 | −4.9% | 1.056 |
| Coraopolis borough | 5,280 | −5% | 1.33 |
| Fox Chapel borough | 5,139 | −3.8% | 7.868 |
| Duquesne city | 5,019 | −4.5% | 1.816 |
| Turtle Creek borough | 4,865 | −4.9% | 0.973 |
| Green Tree borough | 4,672 | −4.8% | 2.075 |
| Avalon borough | 4,572 | −4.8% | 0.617 |
| Bridgeville borough | 4,569 | −4.8% | 1.095 |
| Glassport borough | 4,251 | −4.9% | 1.582 |
| Tarentum borough | 4,127 | −5% | 1.23 |
| North Braddock borough | 4,107 | −4.9% | 1.493 |
| Sewickley borough | 3,729 | −4.6% | 0.999 |
| Port Vue borough | 3,519 | −4.2% | 1.134 |
| Etna borough | 3,269 | −4.8% | 0.736 |
| Springdale borough | 3,234 | −4.9% | 0.934 |
| Ingram borough | 3,222 | −5% | 0.434 |
| Mount Oliver borough | 3,222 | −5% | 0.339 |
| Millvale borough | 3,211 | −4.7% | 0.619 |
| Reserve township | 3,122 | −4.2% | 2.064 |
| Brackenridge borough | 3,093 | −4.7% | 0.513 |
| Churchill borough | 3,014 | −4.9% | 2.188 |
| Harmar township | 2,998 | −4.5% | 5.865 |
| Edgewood borough | 2,997 | −4.4% | 0.588 |
| Sharpsburg borough | 2,990 | −5% | 0.483 |
| Pitcairn borough | 2,953 | −4.9% | 0.506 |
| Forward township | 2,918 | −4.9% | 18.9 |
| Homestead borough | 2,822 | −2.2% | 0.576 |
| Aspinwall borough | 2,809 | −4.9% | 0.351 |
| Verona borough | 2,396 | −4.9% | 0.507 |
| Emsworth borough | 2,377 | −4.9% | 0.569 |
| Crescent township | 2,369 | −4.5% | 2.092 |
| Liberty borough | 2,242 | −5% | 1.43 |
| Fawn township | 2,093 | −4% | 12.9 |
| Rankin borough | 1,975 | +4.3% | 0.433 |
| East McKeesport borough | 1,969 | −5% | 0.413 |
| Baldwin township | 1,896 | −4.4% | 0.505 |
| East Pittsburgh borough | 1,835 | −4.8% | 0.388 |
| Ben Avon borough | 1,824 | −5% | 0.379 |
| West Homestead borough | 1,778 | −4.7% | 0.922 |
| Aleppo township | 1,758 | −3.6% | 1.781 |
| Wilmerding borough | 1,700 | −4.7% | 0.429 |
| Braddock Hills borough | 1,650 | −4.8% | 0.948 |
| Braddock borough | 1,647 | −4.2% | 0.563 |
| Edgeworth borough | 1,611 | −3.8% | 1.496 |
| Cheswick borough | 1,594 | −4.7% | 0.463 |
| Leet township | 1,551 | −4.6% | 1.502 |
| Dravosburg borough | 1,536 | −4.7% | 0.966 |
| Springdale township | 1,463 | −4.8% | 2.253 |
| Bell Acres borough | 1,454 | −3.4% | 5.352 |
| East Deer township | 1,417 | −4.7% | 2.274 |
| Oakdale borough | 1,413 | −4.5% | 0.469 |
| Versailles borough | 1,406 | −5% | 0.484 |
| Blawnox borough | 1,384 | −4.9% | 0.296 |
| Elizabeth borough | 1,343 | −3.9% | 0.343 |
| Heidelberg borough | 1,230 | −4.9% | 0.287 |
| Frazer township | 1,227 | +4.3% | 9.342 |
| Bradford Woods borough | 1,126 | −4.7% | 0.891 |
| Whitaker borough | 1,123 | −5% | 0.296 |
| Leetsdale borough | 1,102 | −4.7% | 0.999 |
| Neville township | 1,052 | −5% | 1.531 |
| Lincoln borough | 888 | −4.5% | 4.8 |
| Sewickley Heights borough | 827 | −3.7% | 7.324 |
| Kilbuck township | 742 | −4.9% | 2.532 |
| Chalfant borough | 710 | −5% | 0.158 |
| Sewickley Hills borough | 681 | −1.3% | 2.466 |
| Pennsbury Village borough | 644 | −4.7% | 0.075 |
| Glen Osborne borough | 558 | −4.9% | 0.43 |
| Wall borough | 493 | −4.8% | 0.437 |
| Thornburg borough | 447 | −5.1% | 0.438 |
| Rosslyn Farms borough | 419 | −5% | 0.555 |
| West Elizabeth borough | 385 | −4.5% | 0.179 |
| Ben Avon Heights borough | 376 | −5.3% | 0.174 |
| McDonald borough | 371 | −5.1% | 0.193 |
| South Versailles township | 303 | −4.4% | 0.867 |
| Glenfield borough | 200 | −4.8% | 0.82 |
| Trafford borough | 90 | −4.3% | 0.245 |
| Haysville borough | 77 | −4.9% | 0.173 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Allegheny County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Allegheny 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; Allegheny County accounts for 12.9% of the land and 50.6% 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
119 ZIP Code Tabulation Areas have land in Allegheny County; 103 of them have most of their land inside the county, and the others mainly cover neighboring areas.
1500315005150061500715014150151501715018150201502415025150261502815030150311503415035150371504415045150461504715049150511505615057150631506415065150681507115075150761508215083150841508515086150881508915090151011510215104151061510815110151121511615120151221512315126151291513115132151331513515136151371513915140151421514315144151451514615147151481520115202152031520415205152061520715208152091521015211152121521315214152151521615217152181521915220152211522215223152241522515226152271522815229152321523315234152351523615237152381523915241152431526015275152821529015321153321564215668160461605516059
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 Allegheny County
Allegheny County shares a land border with 4 county equivalents. It has more land than 1 of them. The largest neighbor is Westmoreland County (1,027.7 mi²) and the smallest is Beaver County (434.7 mi²). Together with its neighbors, Allegheny County forms a block of 3,838.9 mi² of land, of which it holds 19%.
| Bordering county equivalent | Land mi² | Size vs. Allegheny | Compare |
|---|---|---|---|
| Westmoreland County | 1,027.7 | 1.4× larger | Compare |
| Washington County | 857 | 1.2× larger | Compare |
| Butler County | 789.5 | 1.1× larger | Compare |
| Beaver County | 434.7 | 1.7× smaller | Compare |
How big is Allegheny County compared with U.S. states?
Allegheny County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Pennsylvania’s county land could hold about 61 areas the size of Allegheny County.
Another way to picture it: the same land area would fill a square about 27 miles (43.5 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 Allegheny County?
Allegheny County has more land than 2,007 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 Allegheny County at #1,289 nationally by total area, 74 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 1.9%, compared with a national county-equivalent median of 1.2% — 0.8 percentage points higher. 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 Allegheny County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1214 | Amite County, Mississippi | 730.1 | Compare |
| #1215 | Allegheny County, Pennsylvania | 730 | This county |
| #1216 | Morton County, Kansas | 729.7 | 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 40.469757, -79.980451. 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: 1,890,567,444 m²; AWATER: 37,048,385 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 Allegheny County?
Allegheny County, Pennsylvania has 730 square miles (1,890.6 km²) of land and 14.3 square miles of water, for a total area of 744.3 square miles. It ranks #1215 of 3,222 U.S. county equivalents by land area.
Is Allegheny County the largest county in Pennsylvania?
No. Allegheny County ranks #29 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Allegheny County?
Allegheny County shares a land border with Westmoreland County, Washington County, Butler County, and Beaver County.
What is the population of Allegheny County?
The Census Bureau estimates Allegheny County had 1,225,035 residents on July 1, 2025, ranking #39 of 3,222 county equivalents. That is 1,678 people per square mile of land.
What is the county seat of Allegheny County?
The county seat of Allegheny County is Pittsburgh.
What cities and towns are in Allegheny County?
Allegheny County has 130 county subdivisions (cities, towns and townships). The most populous five are Pittsburgh city, Penn Hills municipality, Mount Lebanon municipality, Ross township, and Bethel Park municipality.
Is Allegheny 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 Allegheny County?
119 ZIP Code Tabulation Areas have land in Allegheny County, and 103 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Allegheny County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.4 times as much land.
How many acres of land are in Allegheny County?
The land measurement converts to approximately 467,169 acres. Including water, total area is approximately 476,324 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.