Identifiers: city
| Rank | Community | Population |
|---|---|---|
| 1 | Mason City (city), IA | 27,338 |
| 2 | Clear Lake (city), IA | 7,687 |
| 3 | Garner (city), IA | 3,065 |
| 4 | Northwood (city), IA | 2,072 |
| 5 | Nora Springs (city), IA | 1,369 |
| 6 | Manly (city), IA | 1,256 |
| 7 | Sheffield (city), IA | 1,130 |
| 8 | Rockwell (city), IA | 1,071 |
| 9 | Rockford (city), IA | 758 |
| 10 | Ventura (city), IA | 711 |
| 11 | Thornton (city), IA | 400 |
| 12 | Plymouth (city), IA | 375 |
| 13 | Rudd (city), IA | 358 |
| 14 | Fertile (city), IA | 305 |
| 15 | Kensett (city), IA | 257 |
| 16 | Grafton (city), IA | 216 |
| 17 | Joice (city), IA | 208 |
| 18 | Hanlontown (city), IA | 206 |
| 19 | Rock Falls (city), IA | 150 |
| 20 | Swaledale (city), IA | 144 |