Identifiers: city · town · CDP
| Rank | Community | Population |
|---|---|---|
| 1 | Watertown (city), SD | 22,655 |
| 2 | Castlewood (city), SD | 698 |
| 3 | Florence (town), SD | 337 |
| 4 | Henry (town), SD | 256 |
| 5 | Kranzburg (town), SD | 163 |
| 6 | Goodwin (town), SD | 147 |
| 7 | Wallace (town), SD | 91 |
| 8 | Waverly (CDP), SD | 22 |
Identifiers: city · town · CDP
| Rank | Community | Population |
|---|---|---|
| 1 | Watertown (city), SD | 22,655 |
| 2 | Clear Lake (city), SD | 1,218 |
| 3 | Estelline (city), SD | 749 |
| 4 | Castlewood (city), SD | 698 |
| 5 | Florence (town), SD | 337 |
| 6 | Summit (town), SD | 288 |
| 7 | Henry (town), SD | 256 |
| 8 | South Shore (town), SD | 189 |
| 9 | Kranzburg (town), SD | 163 |
| 10 | Goodwin (town), SD | 147 |
| 11 | Stockholm (town), SD | 102 |
| 12 | Claremont Colony (CDP), SD | 68 |
| 13 | Altamont (town), SD | 32 |
| 14 | Waverly (CDP), SD | 22 |
| 15 | Poinsett Colony (CDP), SD | 5 |