| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wellsville | 1 | 6,831 | 7,022 | -0.41% | 186 | 37 | Town |
| Alfred | 2 | 6,192 | 5,159 | -0.4% | 197 | 31 | Town |
| Alfred | 3 | 5,421 | 4,071 | 5.32% | 4,555 | 1 | Village |
| Wellsville | 4 | 4,479 | 4,624 | -0.56% | 1,848 | 2 | Village |
| Cuba | 5 | 3,062 | 3,121 | -0.1% | 87 | 35 | Town |
| Caneadea | 6 | 2,250 | 2,301 | 1.49% | 63 | 36 | Town |
| Amity | 7 | 2,123 | 2,166 | 0% | 62 | 34 | Town |
| Hume | 8 | 2,030 | 2,075 | -0.29% | 53 | 38 | Town |
| Bolivar | 9 | 1,981 | 2,039 | -0.2% | 55 | 36 | Town |
| Friendship | 10 | 1,922 | 1,944 | -0.21% | 53 | 36 | Town |
| Belfast | 11 | 1,632 | 1,635 | 0.31% | 45 | 36 | Town |
| Scio | 12 | 1,624 | 1,635 | 0.06% | 46 | 35 | Town |
| Genesee | 13 | 1,584 | 1,631 | -0.38% | 44 | 36 | Town |
| Andover | 14 | 1,562 | 1,616 | -0.38% | 40 | 39 | Town |
| Almond | 15 | 1,510 | 1,516 | 0.27% | 33 | 46 | Town |
| Cuba | 16 | 1,479 | 1,535 | -0.74% | 1,216 | 1 | Village |
| Angelica | 17 | 1,282 | 1,279 | 0.39% | 35 | 36 | Town |
| Willing | 18 | 1,241 | 1,282 | -0.4% | 34 | 36 | Town |
| Rushford | 19 | 1,078 | 1,076 | 0.28% | 31 | 35 | Town |
| Independence | 20 | 1,074 | 1,079 | -0.19% | 31 | 34 | Town |
| Burns | 21 | 1,011 | 1,030 | 0% | 37 | 27 | Town |
| Wirt | 22 | 1,001 | 1,034 | -0.4% | 28 | 36 | Town |
| Bolivar | 23 | 998 | 1,033 | -0.7% | 1,252 | 1 | Village |
| Centerville | 24 | 957 | 922 | 0.53% | 27 | 35 | Town |
| Andover | 25 | 875 | 912 | -0.79% | 874 | 1 | Village |
| Belmont | 26 | 820 | 852 | -0.73% | 823 | 1 | Village |
| New Hudson | 27 | 797 | 792 | 0.25% | 22 | 36 | Town |
| North Hornell | 28 | 761 | 782 | -0.52% | 1,550 | 0 | Village |
| Alma | 29 | 758 | 776 | -0.13% | 21 | 36 | Town |
| Angelica | 30 | 702 | 721 | -0.57% | 326 | 2 | Village |
| Granger | 31 | 536 | 517 | 1.52% | 17 | 32 | Town |
| Allen | 32 | 501 | 485 | 0.6% | 14 | 36 | Town |
| Grove | 33 | 497 | 493 | 0% | 15 | 33 | Town |
| Canaseraga | 34 | 447 | 464 | -0.89% | 421 | 1 | Village |
| Richburg | 35 | 393 | 406 | -0.76% | 437 | 1 | Village |
| Almond | 36 | 390 | 406 | -0.76% | 691 | 1 | Village |
| Ward | 37 | 334 | 325 | 1.21% | 11 | 29 | Town |
| West Almond | 38 | 270 | 272 | 0% | 8.0 | 36 | Town |
| Birdsall | 39 | 189 | 186 | 1.07% | 5.0 | 36 | Town |
Wellsville is the largest city in Allegany County, with a population of 6,831.
Birdsall is the smallest city in Allegany County, with a population of 189.
There are 39 cities in Allegany County, New York.