16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gregory | 1 | 1,216 | 1,230 | -0.25% | 707 | 1.72 | City |
| Burke | 2 | 577 | 577 | 0% | 1,032 | 0.56 | City |
| Bonesteel | 3 | 258 | 255 | 0.39% | 729 | 0.35 | City |
| Pleasant Valley township | 4 | 167 | 165 | 0% | 5 | 36.35 | Township |
| Herrick township | 5 | 155 | 149 | 0.65% | 4 | 42.94 | Township |
| Fairfax | 6 | 103 | 98 | 0.98% | 340 | 0.30 | Town |
| Edens township | 7 | 84 | 76 | 3.7% | 2 | 35.70 | Township |
| Dallas | 8 | 83 | 87 | -1.19% | 164 | 0.51 | Town |
| Star Valley township | 9 | 81 | 79 | 0% | 2 | 48.27 | Township |
| Dixon township | 10 | 80 | 79 | 0% | 1 | 64.65 | Township |
| Jones township | 11 | 78 | 76 | 1.3% | 2 | 35.92 | Township |
| Herrick | 12 | 76 | 75 | 0% | 148 | 0.52 | Town |
| Fairfax township | 13 | 64 | 61 | 1.59% | 2 | 32.43 | Township |
| Schriever township | 14 | 41 | 41 | 0% | 2 | 23.77 | Township |
| Landing Creek township | 15 | 19 | 19 | 0% | 0.00 | 61.76 | Township |
| St. Charles | 16 | 9 | 8 | 12.5% | 46 | 0.20 | CDP |
Gregory is the largest city in Gregory County, with a population of 1,216.
St. Charles is the smallest city in Gregory County.
There are 16 cities in Gregory County, South Dakota.