Founded in 1885, Marshall County is one of 66 counties in the state of South Dakota. Historically, Marshall County was formed from Day County. The city of Britton is the county seat. With FIPS code of 91, Marshall County has a population of 4,304 and area of 839 square miles (2,173 km2).
List of all cities in Marshall County, SD alphabetically
| City/Town | Postal Code | Area Code |
| Amherst, SD | 57421 | 605 |
| Britton, SD | 57430 | 605 |
| Eden, SD | 57232 | 605 |
| Hillhead, SD | 57270 | 605 |
| Kidder, SD | 57430 | 605 |
| Lake City, SD | 57247 | 605 |
| Langford, SD | 57454 | 605 |
| Newark, SD | 57430 | 605 |
| Red Iron Lake, SD | 57247 | 605 |
| Spain, SD | 57430 | 605 |
| Sunset Colony, SD | 57430 | 605 |
| Veblen, SD | 57270 | 605 |