Founded in 1913, Jefferson County is one of 44 counties in the state of Idaho. Historically, Jefferson County was formed from Fremont County. The city of Rigby is the county seat. With FIPS code of 51, Jefferson County has a population of 32,202 and area of 1,095 square miles (2,836 km2).
List of all cities in Jefferson County, ID alphabetically
| City/Town | Postal Code | Area Code |
| Annis, ID | 83442 | 208 |
| Hamer, ID | 83425 | 208 |
| Heise, ID | 83443 | 208 |
| Labelle, ID | 83442 | 208 |
| Lewisville, ID | 83431 | 208 |
| Lorenzo, ID | 83442 | 208 |
| Menan, ID | 83434 | 208 |
| Monteview, ID | 83435 | 208 |
| Mud Lake, ID | 83450 | 208 |
| Rigby, ID | 83442 | 208 |
| Ririe, ID | 83443 | 208 |
| Roberts, ID | 83444 | 208 |
| Terreton, ID | 83450 | 208 |