County outline
Where Blair County is located
Area breakdown
Land accounts for 99.8% of Blair County’s measured area and water for 0.2%. Its combined area converts to 1,363.2 square kilometers or approximately 336,857 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 525.067 | 1,359.917 | 336,042.9 |
| Water | 1.272 | 3.294 | 814.1 |
| Total | 526.339 | 1,363.212 | 336,857 |
How Blair County compares
By original Census land area, Blair County ranks #43 of 67 in Pennsylvania and #1993 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.804 times the Pennsylvania county-equivalent median of 653.3 square miles. It accounts for 1.2% of the combined county land area in the state.
See the complete Pennsylvania ranking · What counts as a county equivalent?
Population and density of Blair County
The Census Bureau estimates that 119,541 people lived in Blair County on July 1, 2025. That ranks #546 of 3,222 county equivalents nationally and #28 of 67 in Pennsylvania. Since the April 1, 2020 estimates base of 122,824, the population has declined by 3,283 (−2.7%), compared with +0.4% for Pennsylvania as a whole.
With 525.1 square miles of land, that is 228 people per square mile (88 per km²), placing Blair County #601 nationally for density and #24 in Pennsylvania. The median county equivalent has 47 people per square mile; the Pennsylvania median is 137. Put another way, there are about 2.8 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 122,667 | 122,147 | 120,774 | 120,360 | 120,051 | 119,541 |
| Change | — | −520 | −1,373 | −414 | −309 | −510 |
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 Blair County
Blair County is divided into 25 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 Altoona city, with 42,347 residents (35.4% of the county). The largest by land is Antis township, at 60.8 mi², or 11.6% of the county’s land. The county seat, Hollidaysburg borough, has 5,470 residents. Among those with at least 1,000 residents in 2020, Frankstown township grew fastest since then (+0.8%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Altoona city | 42,347 | −3.6% | 9.791 | 1.9% |
| Logan township | 12,147 | −2.2% | 46.4 | 8.8% |
| Frankstown township | 7,423 | +0.8% | 48.8 | 9.3% |
| Allegheny township | 6,561 | −0.9% | 29.6 | 5.6% |
| Antis township | 6,340 | −2.5% | 60.8 | 11.6% |
| Hollidaysburg boroughCounty seat | 5,470 | −2.4% | 2.334 | 0.4% |
| Tyrone borough | 5,226 | −3.8% | 2.035 | 0.4% |
| Blair township | 4,695 | −2.7% | 13.6 | 2.6% |
| Greenfield township | 3,688 | −3% | 36.1 | 6.9% |
| Snyder township | 3,320 | −2% | 45.1 | 8.6% |
| Freedom township | 2,933 | −2.2% | 17.4 | 3.3% |
| North Woodbury township | 2,416 | −0.9% | 21.1 | 4% |
| Roaring Spring borough | 2,280 | −3.9% | 0.805 | 0.2% |
| Taylor township | 2,255 | −2.3% | 23.3 | 4.4% |
| Tyrone township | 1,814 | −3% | 41.8 | 8% |
Show the other 10 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Martinsburg borough | 1,811 | −3.2% | 0.646 |
| Bellwood borough | 1,748 | −3.7% | 0.476 |
| Woodbury township | 1,414 | −1.5% | 32.5 |
| Huston township | 1,236 | −1% | 34.9 |
| Duncansville borough | 1,207 | −3.7% | 0.532 |
| Williamsburg borough | 1,196 | −3% | 0.367 |
| Juniata township | 939 | −2.6% | 25.6 |
| Catharine township | 750 | −2.8% | 30.7 |
| Newry borough | 221 | −1.8% | 0.098 |
| Tunnelhill borough | 104 | −3.7% | 0.262 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Blair County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Blair County is a central county of the Altoona, PA Metropolitan Statistical Area. Blair County is the area’s only county equivalent, so the metro area has the same 525.1 square miles of land. By combined land it ranks #354 of 393 metropolitan areas, and #338 by population. It belongs to the Altoona-Huntingdon, PA Combined Statistical Area.
ZIP codes
20 ZIP Code Tabulation Areas have land in Blair County; 15 of them have most of their land inside the county, and the others mainly cover neighboring areas.
1594616601166021661316617166251663116635166361663716641166481665516662166651667316682166841668616693
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 Blair County
Blair County shares a land border with 5 county equivalents. Each of them has more land than Blair County. The largest neighbor is Clearfield County (1,144.9 mi²) and the smallest is Cambria County (688 mi²). Together with its neighbors, Blair County forms a block of 5,351.8 mi² of land, of which it holds 9.8%.
| Bordering county equivalent | Land mi² | Size vs. Blair | Compare |
|---|---|---|---|
| Clearfield County | 1,144.9 | 2.2× larger | Compare |
| Centre County | 1,107.3 | 2.1× larger | Compare |
| Bedford County | 1,012 | 1.9× larger | Compare |
| Huntingdon County | 874.6 | 1.7× larger | Compare |
| Cambria County | 688 | 1.3× larger | Compare |
How big is Blair County compared with U.S. states?
Blair 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. Pennsylvania’s county land could hold about 85 areas the size of Blair County.
Another way to picture it: the same land area would fill a square about 22.9 miles (36.9 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 Blair County?
Blair County has more land than 1,229 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 Blair County at #2,084 nationally by total area, 91 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 0.2%, compared with a national county-equivalent median of 1.2% — 0.9 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 Blair County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1992 | Wayne County, Iowa | 525.5 | Compare |
| #1993 | Blair County, Pennsylvania | 525.1 | This county |
| #1994 | Dauphin County, Pennsylvania | 524.9 | 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 40.499979, -78.304063. 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: 1,359,916,284 m²; AWATER: 3,294,803 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 Blair County?
Blair County, Pennsylvania has 525.1 square miles (1,359.9 km²) of land and 1.272 square miles of water, for a total area of 526.3 square miles. It ranks #1993 of 3,222 U.S. county equivalents by land area.
Is Blair County the largest county in Pennsylvania?
No. Blair County ranks #43 of 67 in Pennsylvania by land area. The largest is Lycoming County, with 1,228.9 square miles of land.
What counties border Blair County?
Blair County shares a land border with Huntingdon County, Cambria County, Bedford County, Centre County, and Clearfield County.
What is the population of Blair County?
The Census Bureau estimates Blair County had 119,541 residents on July 1, 2025, ranking #546 of 3,222 county equivalents. That is 228 people per square mile of land.
What is the county seat of Blair County?
The county seat of Blair County is Hollidaysburg.
What cities and towns are in Blair County?
Blair County has 25 county subdivisions (cities, towns and townships). The most populous five are Altoona city, Logan township, Frankstown township, Allegheny township, and Antis township.
Is Blair County part of a metropolitan area?
Yes. It is a central county of the Altoona, PA Metropolitan Statistical Area.
How many ZIP codes are in Blair County?
20 ZIP Code Tabulation Areas have land in Blair County, and 15 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Blair County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2 times as much land.
How many acres of land are in Blair County?
The land measurement converts to approximately 336,043 acres. Including water, total area is approximately 336,857 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.