8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Washington | 1 | 7,189 | 7,346 | -0.43% | 1,330 | 5.41 | City |
| Kalona | 2 | 2,806 | 2,638 | 1.23% | 1,302 | 2.15 | City |
| Wellman | 3 | 1,511 | 1,523 | -0.13% | 1,410 | 1.07 | City |
| Riverside | 4 | 1,036 | 1,060 | -0.48% | 561 | 1.85 | City |
| Brighton | 5 | 583 | 598 | -0.51% | 746 | 0.78 | City |
| Ainsworth | 6 | 516 | 508 | 0.39% | 1,398 | 0.37 | City |
| Crawfordsville | 7 | 278 | 277 | 0% | 757 | 0.37 | City |
| West Chester | 8 | 148 | 145 | 0.68% | 585 | 0.25 | City |
Washington is the largest city in Washington County, with a population of 7,189.
West Chester is the smallest city in Washington County.
There are 8 cities in Washington County, Iowa.