Founded in 1813, Washington County is one of 114 counties in the state of Missouri. Historically, Washington County was formed from Sainte Genevieve County. The city of Potosi is the county seat. With FIPS code of 221, Washington County has a population of 23,502 and area of 760 square miles (1,968 km2).
List of all cities in Washington County, MO alphabetically
| City/Town | Postal Code | Area Code |
| Belgrade, MO | 63622 | 573 |
| Cadet, MO | 63630 | 573 |
| Caledonia, MO | 63631 | 573 |
| Hopewell, MO | 63660 | 573 |
| Irondale, MO | 63648 | 573 |
| Mineral Point, MO | 63660 | 573 |
| Old Mines, MO | 63630 | 573 |
| Potosi, MO | 63664 | 573 |
| Richwoods, MO | 63071 | 573 |
| Springtown, MO | 63660 | 573 |
| Stoney Point, MO | 63660 | 573 |
| Tiff, MO | 63674 | 573 |