16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gregory | 1 | 1,279 | 1,231 | 0.71% | 743 | 2 | City |
| Burke | 2 | 592 | 580 | 0.34% | 1,059 | 1 | City |
| Bonesteel | 3 | 260 | 253 | 0.39% | 734 | 0 | City |
| Pleasant Valley | 4 | 171 | 163 | 1.79% | 5 | 36 | Township |
| Herrick | 5 | 153 | 149 | 0% | 4 | 43 | Township |
| Fairfax | 6 | 104 | 99 | 0.97% | 343 | 0 | Town |
| Dallas | 7 | 85 | 87 | -1.16% | 168 | 1 | Town |
| Dixon | 8 | 83 | 79 | 1.22% | 1 | 65 | Township |
| Jones | 9 | 82 | 76 | 3.8% | 2 | 36 | Township |
| Star Valley | 10 | 82 | 78 | 1.23% | 2 | 48 | Township |
| Herrick | 11 | 77 | 75 | 0% | 150 | 1 | Town |
| Edens | 12 | 77 | 73 | 1.32% | 2 | 36 | Township |
| Fairfax | 13 | 64 | 60 | 3.23% | 2 | 32 | Township |
| Schriever | 14 | 42 | 40 | 2.44% | 2 | 24 | Township |
| Landing Creek | 15 | 20 | 20 | 0% | 0.00 | 62 | Township |
| St. Charles | 16 | 9 | 8 | 12.5% | 46 | 0 | CDP |
Gregory is the largest city in Gregory County, with a population of 1,279.
St. Charles is the smallest city in Gregory County, with a population of 9.
There are 16 cities in Gregory County, South Dakota.