Founded in 1873, Lake County is one of 66 counties in the state of South Dakota. Historically, Lake County was formed from Brookings and Hanson counties. The city of Madison is the county seat. With FIPS code of 79, Lake County has a population of 10,851 and area of 563 square miles (1,458 km2).
List of all cities in Lake County, SD alphabetically
| City/Town | Postal Code | Area Code |
| Chester, SD | 57016 | 605 |
| Franklin, SD | 57016 | 605 |
| Junius, SD | 57042 | 605 |
| Lake Brandt, SD | 57016 | 605 |
| Lake Herman, SD | 57042 | 605 |
| Lake Madison, SD | 57075 | 605 |
| Madison, SD | 57042 | 605 |
| Nunda, SD | 57050 | 605 |
| Orland, SD | 57042 | 605 |
| Ramona, SD | 57054 | 605 |
| Rutland, SD | 57057 | 605 |
| Smiths Park, SD | 57075 | 605 |
| Wentworth, SD | 57075 | 605 |
| Winfred, SD | 57076 | 605 |