Founded in 1914, Jefferson County is one of 36 counties in the state of Oregon. Historically, Jefferson County was formed from Crook County. The city of Madras is the county seat. With FIPS code of 31, Jefferson County has a population of 25,068 and area of 1,781 square miles (4,613 km2).
List of all cities in Jefferson County, OR alphabetically
| City/Town | Postal Code | Area Code |
| Ashwood, OR | 97711 | 541 |
| Camp Sherman, OR | 97730 | 541 |
| Crooked River Ranch, OR | 97760 | 541 |
| Culver, OR | 97734 | 541 |
| Kah Nee Ta, OR | 97761 | 541 |
| Kahneeta, OR | 97761 | 541 |
| Madras, OR | 97741 | 541 |
| Metolius, OR | 97741 | 541 |
| Terrebonne, OR | 97760 | 541 |
| Warm Springs, OR | 97761 | 541 |