23 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Altoona | 1 | 42,048 | 43,898 | -0.87% | 4,295 | 9.79 | City |
| Logan township | 2 | 12,083 | 12,388 | -0.36% | 261 | 46.38 | Township |
| Frankstown township | 3 | 7,720 | 7,400 | 1.54% | 158 | 48.82 | Township |
| Allegheny township | 4 | 6,504 | 6,575 | -0.21% | 220 | 29.62 | Township |
| Antis township | 5 | 6,278 | 6,480 | -0.55% | 103 | 60.76 | Township |
| Hollidaysburg | 6 | 5,418 | 5,638 | -0.81% | 2,325 | 2.33 | Borough |
| Tyrone | 7 | 5,234 | 5,469 | -0.89% | 2,572 | 2.04 | Borough |
| Blair township | 8 | 4,622 | 4,779 | -0.58% | 339 | 13.62 | Township |
| Greenfield township | 9 | 3,656 | 3,782 | -0.54% | 101 | 36.09 | Township |
| Snyder township | 10 | 3,278 | 3,343 | -0.21% | 73 | 45.13 | Township |
| North Woodbury township | 11 | 2,401 | 2,432 | -0.08% | 114 | 21.06 | Township |
| Tyrone township | 12 | 2,355 | 2,269 | 0.9% | 110 | 21.49 | Township |
| Roaring Spring | 13 | 2,273 | 2,378 | -0.92% | 2,824 | 0.81 | Borough |
| Tyrone township | 14 | 1,923 | 1,919 | -0.16% | 54 | 35.67 | Township |
| Tyrone township | 15 | 1,810 | 1,866 | -0.33% | 43 | 41.82 | Township |
| Martinsburg | 16 | 1,798 | 1,877 | -0.88% | 2,783 | 0.65 | Borough |
| Bellwood | 17 | 1,741 | 1,820 | -0.91% | 3,658 | 0.48 | Borough |
| Huston township | 18 | 1,238 | 1,248 | 0% | 35 | 34.89 | Township |
| Duncansville | 19 | 1,194 | 1,249 | -0.91% | 2,244 | 0.53 | Borough |
| Williamsburg | 20 | 1,177 | 1,229 | -0.84% | 3,207 | 0.37 | Borough |
| Tunnelhill | 21 | 304 | 318 | -0.98% | 615 | 0.49 | Borough |
| Newry | 22 | 227 | 237 | -0.87% | 2,316 | 0.10 | Borough |
| Birmingham | 23 | 85 | 89 | -1.16% | 1,349 | 0.06 | Borough |
Altoona is the largest city in Blair County, with a population of 42,048.
Birmingham is the smallest city in Blair County.
There are 23 cities in Blair County, Pennsylvania.