Founded in 1873, Douglas County is one of 66 counties in the state of South Dakota. Historically, Douglas County was formed from Charles Mix County. The city of Armour is the county seat. With FIPS code of 43, Douglas County has a population of 2,821 and area of 434 square miles (1,124 km2).
List of all cities in Douglas County, SD alphabetically
| City/Town | Postal Code | Area Code |
| Armour, SD | 57313 | 605 |
| Corsica, SD | 57328 | 605 |
| Delmont, SD | 57330 | 605 |
| Harrison, SD | 57344 | 605 |
| Joubert, SD | 57364 | 605 |
| New Holland, SD | 57364 | 605 |