Post Offices List in Lake County, South Dakota:
| Chester Post Office | 410 4th St, Chester, SD 57016 |
| Madison Post Office | 119 E Center St, Madison, SD 57042 |
| Nunda Post Office | 409 Main St, Nunda, SD 57050 |
| Ramona Post Office | 217 E Main St, Ramona, SD 57054 |
| Wentworth Post Office | 107 S Main Ave, Wentworth, SD 57075 |
| Winfred Post Office | 352 Main St, Winfred, SD 57076 |