21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 1,311 | 1,328 | -0.3% | 1,049 | 1 | City |
| Canistota | 2 | 646 | 630 | 0.47% | 1,152 | 1 | City |
| Bridgewater | 3 | 504 | 509 | -0.2% | 448 | 1 | City |
| Montrose | 4 | 459 | 466 | -0.43% | 1,090 | 0 | City |
| Spring Valley | 5 | 384 | 368 | 0% | 11 | 36 | Township |
| Greenland | 6 | 331 | 321 | -0.9% | 10 | 35 | Township |
| Salem | 7 | 277 | 268 | 0% | 8 | 35 | Township |
| Montrose | 8 | 219 | 212 | -0.45% | 6 | 35 | Township |
| Richland | 9 | 168 | 163 | -1.18% | 5 | 36 | Township |
| Grant | 10 | 155 | 150 | -1.27% | 4 | 36 | Township |
| Canistota | 11 | 154 | 151 | -1.91% | 4 | 36 | Township |
| Sun Prairie | 12 | 138 | 131 | 0.73% | 4 | 36 | Township |
| Spencer | 13 | 136 | 136 | 0% | 507 | 0 | City |
| Salem | 14 | 135 | 131 | -0.74% | 4 | 36 | Township |
| Brookfield | 15 | 133 | 128 | 0% | 4 | 36 | Township |
| Union | 16 | 127 | 122 | 0% | 4 | 36 | Township |
| Bridgewater | 17 | 121 | 117 | -0.82% | 4 | 35 | Township |
| Ramsey | 18 | 99 | 97 | -1% | 3 | 36 | Township |
| Benton | 19 | 97 | 95 | -1.02% | 3 | 35 | Township |
| Pearl | 20 | 59 | 55 | 1.72% | 2 | 36 | Township |
| Orland Colony | 21 | 49 | 29 | 6.52% | 97 | 1 | CDP |
Salem is the largest city in McCook County, with a population of 1,311.
Orland Colony is the smallest city in McCook County, with a population of 49.
There are 21 cities in McCook County, South Dakota.