| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Grinnell | 1 | 9,415 | 9,539 | -0.16% | 1,655 | 6 | City |
| Brooklyn | 2 | 1,460 | 1,501 | -0.48% | 1,110 | 1 | City |
| Montezuma | 3 | 1,410 | 1,446 | -0.49% | 571 | 2 | City |
| Malcom | 4 | 256 | 269 | -1.16% | 310 | 1 | City |
| Deep River | 5 | 244 | 248 | -0.41% | 558 | 0 | City |
| Searsboro | 6 | 127 | 130 | -0.78% | 282 | 0 | City |
| Hartwick | 7 | 90 | 92 | -1.1% | 570 | 0 | City |
| Guernsey | 8 | 60 | 62 | -1.64% | 107 | 1 | City |
Grinnell is the largest city in Poweshiek County, with a population of 9,415.
Guernsey is the smallest city in Poweshiek County, with a population of 60.
There are 8 cities in Poweshiek County, Iowa.