9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cannon Ball | 1 | 901 | 943 | 0.11% | 10 | 88.27 | CDP |
| McLaughlin | 2 | 537 | 566 | -1.1% | 1,329 | 0.40 | City |
| Kenel | 3 | 220 | 146 | 7.32% | 224 | 0.98 | CDP |
| Fort Yates | 4 | 158 | 177 | -2.47% | 2,633 | 0.06 | City |
| Selfridge | 5 | 112 | 126 | -2.61% | 380 | 0.29 | City |
| Porcupine | 6 | 108 | 162 | -2.7% | 535 | 0.20 | CDP |
| Solen | 7 | 61 | 70 | -3.17% | 183 | 0.33 | City |
| Cannon Ball township | 8 | 39 | 40 | 0% | 1 | 36.02 | Township |
| Menz township | 9 | 18 | 19 | 0% | 0.00 | 46.66 | Township |
Cannon Ball is the largest city in Sioux County, with a population of 901.
Menz township is the smallest city in Sioux County.
There are 9 cities in Sioux County, North Dakota.