Founded on Jan 25, 1839, Washington County is one of 99 counties in the state of Iowa. Historically, Washington County was formed from Wisconsin Territory. The city of Washington is the county seat. With FIPS code of 183, Washington County has a population of 22,491 and area of 569 square miles (1,474 km2).
List of all cities in Washington County, IA alphabetically
| City/Town | Postal Code | Area Code |
| Ainsworth, IA | 52201 | 319 |
| Brighton, IA | 52540 | 319 |
| Crawfordsville, IA | 52621 | 319 |
| Daytonville, IA | 52356 | 319 |
| East Pleasant Plain, IA | 52540 | 319 |
| Frytown, IA | 52247 | 319 |
| Germanville, IA | 52540 | 319 |
| Grace Hill, IA | 52353 | 319 |
| Haskins, IA | 52201 | 319 |
| Joetown, IA | 52247 | 319 |
| Kalona, IA | 52247 | 319 |
| Pleasant Plain, IA | 52540 | 319 |
| Riverside, IA | 52327 | 319 |
| Washington, IA | 52353 | 319 |
| Wellman, IA | 52356 | 319 |
| West Chester, IA | 52359 | 319 |
| Williamstown, IA | 52247 | 319 |
| Wyman, IA | 52621 | 319 |