| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lima | 1 | 34,527 | 35,476 | -0.48% | 2,535 | 14 | City |
| Delphos | 2 | 7,085 | 7,114 | -0.16% | 2,133 | 3 | City |
| Bluffton | 3 | 3,857 | 3,962 | -0.46% | 1,044 | 4 | Village |
| Spencerville | 4 | 2,155 | 2,204 | -0.46% | 2,233 | 1 | Village |
| Elida | 5 | 1,899 | 1,919 | -0.26% | 1,630 | 1 | Village |
| Cridersville | 6 | 1,756 | 1,809 | -0.62% | 1,463 | 1 | Village |
| Cairo | 7 | 504 | 517 | -0.59% | 1,819 | 0 | Village |
| McGuffey | 8 | 451 | 463 | -0.66% | 1,212 | 0 | Village |
| Harrod | 9 | 426 | 424 | 0% | 1,821 | 0 | Village |
| Lafayette | 10 | 399 | 406 | -0.5% | 1,712 | 0 | Village |
| Beaverdam | 11 | 309 | 319 | -0.64% | 490 | 1 | Village |
Lima is the largest city in Allen County, with a population of 34,527.
Beaverdam is the smallest city in Allen County, with a population of 309.
There are 11 cities in Allen County, Ohio.