Founded in 1841, Saint Clair County is one of 114 counties in the state of Missouri. Historically, Saint Clair County was formed from Rives (now Henry) County. The city of Osceola is the county seat. With FIPS code of 185, Saint Clair County has a population of 9,376 and area of 677 square miles (1,753 km2).
List of all cities in Saint Clair County, MO alphabetically
| City/Town | Postal Code | Area Code |
| Appleton City, MO | 64724 | 660 |
| Collins, MO | 64738 | 417 |
| Damascus, MO | 64776 | 417 |
| Lowry City, MO | 64763 | 417 |
| Osceola, MO | 64776 | 417 |
| Roscoe, MO | 64781 | 417 |
| Vista, MO | 64776 | 417 |