Founded in 1841, Oregon County is one of 114 counties in the state of Missouri. Historically, Oregon County was formed from Ripley County. The city of Alton is the county seat. With FIPS code of 149, Oregon County has a population of 8,631 and area of 792 square miles (2,051 km2).
List of all cities in Oregon County, MO alphabetically
| City/Town | Postal Code | Area Code |
| Alton, MO | 65606 | 417 |
| Couch, MO | 65690 | 417 |
| Koshkonong, MO | 65692 | 417 |
| Myrtle, MO | 65778 | 417 |
| Thayer, MO | 65791 | 417 |