Identifiers: city
| Rank | Community | Population |
|---|---|---|
| 1 | Mason City (city), IA | 27,338 |
| 2 | Clear Lake (city), IA | 7,687 |
| 3 | Forest City (city), IA | 4,285 |
| 4 | Garner (city), IA | 3,065 |
| 5 | Britt (city), IA | 2,044 |
| 6 | Nora Springs (city), IA | 1,369 |
| 7 | Manly (city), IA | 1,256 |
| 8 | Rockwell (city), IA | 1,071 |
| 9 | Ventura (city), IA | 711 |
| 10 | Latimer (city), IA | 477 |
| 11 | Klemme (city), IA | 441 |
| 12 | Thornton (city), IA | 400 |
| 13 | Plymouth (city), IA | 375 |
| 14 | Rudd (city), IA | 358 |
| 15 | Fertile (city), IA | 305 |
| 16 | Kensett (city), IA | 257 |
| 17 | Meservey (city), IA | 222 |
| 18 | Coulter (city), IA | 219 |
| 19 | Joice (city), IA | 208 |
| 20 | Hanlontown (city), IA | 206 |