Founded in 1915, Gem County is one of 44 counties in the state of Idaho. Historically, Gem County was formed from Boise and Canyon Counties. The city of Emmett is the county seat. With FIPS code of 45, Gem County has a population of 19,792 and area of 563 square miles (1,458 km2).
List of all cities in Gem County, ID alphabetically
| City/Town | Postal Code | Area Code |
| Emmett, ID | 83617 | 208 |
| Gross, ID | 83657 | 208 |
| Letha, ID | 83636 | 208 |
| Montour, ID | 83617 | 208 |
| Ola, ID | 83657 | 208 |
| Sweet, ID | 83670 | 208 |