9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cannon Ball | 1 | 901 | 943 | 0.11% | 10 | 88 | CDP |
| McLaughlin | 2 | 535 | 564 | -1.11% | 1,324 | 0 | City |
| Kenel | 3 | 220 | 146 | 7.32% | 224 | 1 | CDP |
| Fort Yates | 4 | 170 | 177 | -1.16% | 2,833 | 0 | City |
| Selfridge | 5 | 119 | 126 | -1.65% | 403 | 0 | City |
| Porcupine | 6 | 108 | 162 | -2.7% | 535 | 0 | CDP |
| Solen | 7 | 66 | 71 | -1.49% | 198 | 0 | City |
| Cannon Ball | 8 | 39 | 39 | 0% | 1 | 36 | Township |
| Menz | 9 | 17 | 18 | 0% | 0.00 | 47 | Township |
Cannon Ball is the largest city in Sioux County, with a population of 901.
Menz is the smallest city in Sioux County, with a population of 17.
There are 9 cities in Sioux County, North Dakota.