County outline
Where Armstrong County is located
Area breakdown
Land accounts for 98.4% of Armstrong County’s measured area and water for 1.6%. Its combined area converts to 1,719.7 square kilometers or approximately 424,942 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 653.321 | 1,692.094 | 418,125.4 |
| Water | 10.651 | 27.586 | 6,816.6 |
| Total | 663.972 | 1,719.68 | 424,942.1 |
How Armstrong County compares
By original Census land area, Armstrong County ranks #34 of 67 in Pennsylvania and #1441 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 1.5% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Armstrong County
The Census Bureau estimates that 63,698 people lived in Armstrong County on July 1, 2025. That ranks #869 of 3,222 county equivalents nationally and #40 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 65,572, the population has declined by 1,874 (−2.9%), compared with +0.4% for Pennsylvania as a whole.
With 653.3 square miles of land, that is 97 people per square mile (38 per km²), placing Armstrong County #1,011 nationally for density and #41 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 6.6 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 65,496 | 65,283 | 64,724 | 64,157 | 63,755 | 63,698 |
| Change | — | −213 | −559 | −567 | −402 | −57 |
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 Armstrong County
Armstrong County is divided into 45 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 Kiskiminetas township, with 4,522 residents (7.1% of the county). The largest by land is Cowanshannock township, at 45.7 mi², or 7% of the county’s land. The county seat, Kittanning borough, has 3,941 residents. Among those with at least 1,000 residents in 2020, Kittanning borough grew fastest since then (+0.3%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Kiskiminetas township | 4,522 | −2.1% | 40.7 | 6.2% |
| Manor township | 4,068 | −3.1% | 16.6 | 2.5% |
| Kittanning boroughCounty seat | 3,941 | +0.3% | 0.996 | 0.2% |
| East Franklin township | 3,699 | −3% | 30.9 | 4.7% |
| Ford City borough | 2,750 | −4% | 0.645 | 0.1% |
| South Buffalo township | 2,674 | −1.5% | 27.3 | 4.2% |
| Cowanshannock township | 2,656 | −2.7% | 45.7 | 7% |
| North Buffalo township | 2,611 | −3.1% | 24.9 | 3.8% |
| Parks township | 2,388 | −3.4% | 14 | 2.1% |
| Gilpin township | 2,333 | −3.1% | 16.5 | 2.5% |
| Leechburg borough | 2,068 | −3.8% | 0.439 | 0.1% |
| Plumcreek township | 2,041 | −3.2% | 42.4 | 6.5% |
| Kittanning townshipCounty seat | 2,002 | −1.4% | 30.7 | 4.7% |
| Rayburn township | 1,716 | −3.3% | 11.8 | 1.8% |
| Freeport borough | 1,672 | −3.9% | 1.27 | 0.2% |
Show the other 30 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| West Franklin township | 1,655 | −3.1% | 26.1 |
| Apollo borough | 1,537 | −3.9% | 0.305 |
| Mahoning township | 1,364 | −2.9% | 24.8 |
| Sugarcreek township | 1,333 | −1.3% | 26.7 |
| Wayne township | 1,262 | −3.1% | 44.7 |
| North Apollo borough | 1,212 | −3.7% | 0.543 |
| West Kittanning borough | 1,152 | −3.9% | 0.429 |
| Bethel township | 1,068 | −3.2% | 15.3 |
| South Bend township | 980 | −2.9% | 22.5 |
| Redbank township | 935 | −3.9% | 32.3 |
| Washington township | 866 | −2.7% | 22.5 |
| Rural Valley borough | 798 | −3.7% | 2.111 |
| Madison township | 796 | −3.5% | 30 |
| Boggs township | 781 | −3.2% | 24.6 |
| Bradys Bend township | 761 | −2.9% | 12.6 |
| Parker city | 674 | −3.6% | 0.956 |
| Burrell township | 636 | −2.9% | 21.5 |
| Valley township | 629 | −3.5% | 14.7 |
| Worthington borough | 566 | −3.9% | 0.688 |
| Dayton borough | 528 | −3.8% | 0.376 |
| South Bethlehem borough | 464 | −3.9% | 0.152 |
| Manorville borough | 364 | −3.4% | 0.101 |
| Perry township | 362 | −1.4% | 15 |
| Pine township | 347 | −3.3% | 4.344 |
| Ford Cliff borough | 346 | −4.2% | 0.076 |
| Applewold borough | 324 | −4.1% | 0.047 |
| Elderton borough | 322 | −3.6% | 0.323 |
| Cadogan township | 320 | −3.6% | 0.976 |
| Atwood borough | 104 | −3.7% | 2.092 |
| Hovey township | 71 | −4.1% | 1.842 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Armstrong County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Armstrong County is an outlying 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; Armstrong County accounts for 11.6% of the land and 2.6% 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
37 ZIP Code Tabulation Areas have land in Armstrong County; 27 of them have most of their land inside the county, and the others mainly cover neighboring areas.
15613156181565615673156821568615690157321573615774160251602816041160491605516201162101621216218162221622316224162261622816229162361623816240162421624416245162491625016253162591626216263
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 Armstrong County
Armstrong County shares a land border with 5 county equivalents. It has more land than 2 of them. The largest neighbor is Westmoreland County (1,027.7 mi²) and the smallest is Clarion County (600.8 mi²). Together with its neighbors, Armstrong County forms a block of 4,551.2 mi² of land, of which it holds 14.4%.
| Bordering county equivalent | Land mi² | Size vs. Armstrong | Compare |
|---|---|---|---|
| Westmoreland County | 1,027.7 | 1.6× larger | Compare |
| Indiana County | 827.4 | 1.3× larger | Compare |
| Butler County | 789.5 | 1.2× larger | Compare |
| Jefferson County | 652.5 | about the same | Compare |
| Clarion County | 600.8 | 1.1× smaller | Compare |
How big is Armstrong County compared with U.S. states?
Armstrong County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.6 times as much. Pennsylvania’s county land could hold about 68 areas the size of Armstrong County.
Another way to picture it: the same land area would fill a square about 25.6 miles (41.1 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 Armstrong County?
Armstrong County has more land than 1,781 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 Armstrong County at #1,529 nationally by total area, 88 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 1.6%, compared with a national county-equivalent median of 1.2% — 0.4 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 Armstrong County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1440 | Olmsted County, Minnesota | 653.5 | Compare |
| #1441 | Armstrong County, Pennsylvania | 653.3 | This county |
| #1442 | Cumberland County, North Carolina | 652.6 | 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 40.812380, -79.464129. 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: 1,692,093,645 m²; AWATER: 27,586,722 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 Armstrong County?
Armstrong County, Pennsylvania has 653.3 square miles (1,692.1 km²) of land and 10.7 square miles of water, for a total area of 664 square miles. It ranks #1441 of 3,222 U.S. county equivalents by land area.
Is Armstrong County the largest county in Pennsylvania?
No. Armstrong County ranks #34 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Armstrong County?
Armstrong County shares a land border with Clarion County, Butler County, Indiana County, Westmoreland County, and Jefferson County.
What is the population of Armstrong County?
The Census Bureau estimates Armstrong County had 63,698 residents on July 1, 2025, ranking #869 of 3,222 county equivalents. That is 97 people per square mile of land.
What is the county seat of Armstrong County?
The county seat of Armstrong County is Kittanning.
What cities and towns are in Armstrong County?
Armstrong County has 45 county subdivisions (cities, towns and townships). The most populous five are Kiskiminetas township, Manor township, Kittanning borough, East Franklin township, and Ford City borough.
Is Armstrong County part of a metropolitan area?
Yes. It is an outlying county of the Pittsburgh, PA Metropolitan Statistical Area, which has 8 county equivalents and 2,421,992 residents.
How many ZIP codes are in Armstrong County?
37 ZIP Code Tabulation Areas have land in Armstrong County, and 27 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Armstrong County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.6 times as much land.
How many acres of land are in Armstrong County?
The land measurement converts to approximately 418,125 acres. Including water, total area is approximately 424,942 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.