Towns
| State | City/Town | Town Title |
|---|---|---|
| Illinois | Steeleville | Steeleville, IL |
| Illinois | Steger | Steger, IL |
| Illinois | Sterling | Sterling, IL |
| Illinois | Steward | Steward, IL |
| Illinois | Stewardson | Stewardson, IL |
| Illinois | Stillman Valley | Stillman Valley, IL |
| Illinois | Stockland | Stockland, IL |
| Illinois | Stockton | Stockton, IL |
| Illinois | Stone Park | Stone Park, IL |
| Illinois | Stonefort | Stonefort, IL |
| Illinois | Stonington | Stonington, IL |
| Illinois | Stoy | Stoy, IL |
| Illinois | Strasburg | Strasburg, IL |
| Illinois | Strawn | Strawn, IL |
| Illinois | Streamwood | Streamwood, IL |
| Illinois | Streator | Streator, IL |
| Illinois | Stronghurst | Stronghurst, IL |
| Illinois | Sublette | Sublette, IL |
| Illinois | Sugar Grove | Sugar Grove, IL |
| Illinois | Sullivan | Sullivan, IL |
| Illinois | Summerfield | Summerfield, IL |
| Illinois | Summit Argo | Summit Argo, IL |
| Illinois | Sumner | Sumner, IL |
| Illinois | Sutter | Sutter, IL |
| Illinois | Swansea | Swansea, IL |