| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Eagle Butte | 1 | 1,273 | 1,247 | 0.32% | 935 | 1 | City |
| Timber Lake | 2 | 556 | 512 | 1.46% | 910 | 1 | City |
| Isabel | 3 | 164 | 144 | 1.23% | 194 | 1 | Town |
Eagle Butte is the largest city in Dewey County, with a population of 1,273.
Isabel is the smallest city in Dewey County, with a population of 164.
There are 3 cities in Dewey County, South Dakota.