21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 1,337 | 1,331 | 0.07% | 1,070 | 1.25 | City |
| Canistota | 2 | 649 | 631 | 0.62% | 1,157 | 0.56 | City |
| Bridgewater | 3 | 506 | 508 | 0% | 450 | 1.13 | City |
| Montrose | 4 | 468 | 463 | 0.21% | 1,112 | 0.42 | City |
| Spring Valley township | 5 | 396 | 369 | 1.54% | 11 | 35.80 | Township |
| Greenland township | 6 | 348 | 322 | 1.46% | 10 | 34.74 | Township |
| Salem township | 7 | 286 | 271 | 0.7% | 8 | 34.64 | Township |
| Montrose township | 8 | 228 | 213 | 1.33% | 6 | 35.42 | Township |
| Richland township | 9 | 177 | 162 | 1.72% | 5 | 35.91 | Township |
| Canistota township | 10 | 167 | 152 | 1.83% | 5 | 35.66 | Township |
| Grant township | 11 | 162 | 147 | 1.89% | 4 | 36.11 | Township |
| Brookfield township | 12 | 138 | 127 | 1.47% | 4 | 36.45 | Township |
| Spencer | 13 | 137 | 137 | 0% | 511 | 0.27 | City |
| Salem township | 14 | 137 | 130 | 0.74% | 4 | 36.35 | Township |
| Sun Prairie township | 15 | 136 | 131 | 0% | 4 | 36.48 | Township |
| Union township | 16 | 129 | 124 | 0% | 4 | 36.07 | Township |
| Bridgewater township | 17 | 116 | 112 | 0% | 3 | 34.56 | Township |
| Ramsey township | 18 | 103 | 99 | 0% | 3 | 36.07 | Township |
| Benton township | 19 | 98 | 90 | 2.08% | 3 | 35.16 | Township |
| Pearl township | 20 | 57 | 55 | 0% | 2 | 36.35 | Township |
| Orland Colony | 21 | 49 | 29 | 6.52% | 97 | 0.51 | CDP |
Salem is the largest city in McCook County, with a population of 1,337.
Orland Colony is the smallest city in McCook County.
There are 21 cities in McCook County, South Dakota.