21 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Star | Ada County | 21,579 |
| Sandpoint | Bonner County | 11,300 |
| Shelley | Bingham County | 5,472 |
| St. Anthony | Fremont County | 4,286 |
| Salmon | Lemhi County | 3,337 |
| Soda Springs | Caribou County | 3,186 |
| Sugar City | Madison County | 2,726 |
| St. Maries | Benewah County | 2,548 |
| Spirit Lake | Kootenai County | 2,524 |
| Shoshone | Lincoln County | 1,805 |
| Sun Valley | Blaine County | 1,761 |
| Silverton | Shoshone County | 746 |
| Smelterville | Shoshone County | 723 |
| Swan Valley | Bonneville County | 345 |
| St. Charles | Bear Lake County | 196 |
| Stites | Idaho County | 194 |
| Sweetwater | Nez Perce County | 174 |
| Stanley | Custer County | 125 |
| Smiths Ferry | Idaho County | 65 |
| State Line | Kootenai County | 38 |
| Spencer | Clark County | 31 |