17 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lima | 1 | 34,293 | 35,483 | -0.57% | 2,518 | 14 | City |
| American | 2 | 14,491 | 14,563 | 0.16% | 603 | 24 | Township |
| Delphos | 3 | 7,053 | 7,115 | -0.14% | 2,123 | 3 | City |
| Lafayette | 4 | 6,259 | 6,074 | 0.55% | 273 | 23 | Township |
| Richland | 5 | 5,729 | 5,883 | -0.4% | 138 | 42 | Township |
| Lafayette | 6 | 4,364 | 4,281 | 0.37% | 177 | 25 | Township |
| Bluffton | 7 | 3,839 | 3,964 | -0.54% | 1,039 | 4 | Village |
| Auglaize | 8 | 2,843 | 2,763 | 0.42% | 79 | 36 | Township |
| Spencerville | 9 | 2,145 | 2,202 | -0.42% | 2,223 | 1 | Village |
| Elida | 10 | 1,893 | 1,926 | -0.26% | 1,625 | 1 | Village |
| Cridersville | 11 | 1,719 | 1,796 | -0.75% | 1,433 | 1 | Village |
| Sugar Creek | 12 | 1,195 | 1,224 | -0.08% | 50 | 24 | Township |
| Cairo | 13 | 503 | 518 | -0.4% | 1,816 | 0 | Village |
| McGuffey | 14 | 454 | 463 | -0.22% | 1,220 | 0 | Village |
| Harrod | 15 | 426 | 429 | 0% | 1,821 | 0 | Village |
| Lafayette | 16 | 392 | 401 | -0.25% | 1,682 | 0 | Village |
| Beaverdam | 17 | 310 | 321 | -0.64% | 492 | 1 | Village |
Lima is the largest city in Allen County, with a population of 34,293.
Beaverdam is the smallest city in Allen County, with a population of 310.
There are 17 cities in Allen County, Ohio.