Post Offices List in Madison County, Ohio:
| Irwin Post Office | 24176 State Route 161, Irwin, OH 43029 |
| London Post Office | 25 S Oak St, London, OH 43140 |
| Mount Sterling Post Office | 34 W Columbus St, Mount Sterling, OH 43143 |
| Plain City Post Office | 219 Maple St, Plain City, OH 43064 |
| Sedalia Post Office | 61 Federal St Sw, Sedalia, OH 43151 |
| South Solon Post Office | 7230 E Main St, South Solon, OH 43153 |
| West Jefferson Post Office | 249 W Main St, West Jefferson, OH 43162 |