5 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cannon Ball | 1 | 901 | 943 | 0.11% | 10 | 88.27 | CDP |
| Fort Yates | 2 | 158 | 177 | -2.47% | 2,633 | 0.06 | City |
| Selfridge | 3 | 112 | 126 | -2.61% | 380 | 0.29 | City |
| Porcupine | 4 | 108 | 162 | -2.7% | 535 | 0.20 | CDP |
| Solen | 5 | 61 | 70 | -3.17% | 183 | 0.33 | City |
Cannon Ball is the largest city in Sioux County, with a population of 901.
Solen is the smallest city in Sioux County.
There are 5 cities in Sioux County, North Dakota.