Towns
| State | City/Town | Town Title |
|---|---|---|
| Illinois | Simpson | Simpson, IL |
| Illinois | Sims | Sims, IL |
| Illinois | Skokie | Skokie, IL |
| Illinois | Smithboro | Smithboro, IL |
| Illinois | Smithfield | Smithfield, IL |
| Illinois | Smithshire | Smithshire, IL |
| Illinois | Smithton | Smithton, IL |
| Illinois | Somonauk | Somonauk, IL |
| Illinois | Sorento | Sorento, IL |
| Illinois | South Beloit | South Beloit, IL |
| Illinois | South Elgin | South Elgin, IL |
| Illinois | South Holland | South Holland, IL |
| Illinois | South Pekin | South Pekin, IL |
| Illinois | South Roxana | South Roxana, IL |
| Illinois | South Wilmington | South Wilmington, IL |
| Illinois | Sparland | Sparland, IL |
| Illinois | Sparta | Sparta, IL |
| Illinois | Speer | Speer, IL |
| Illinois | Spring Grove | Spring Grove, IL |
| Illinois | Spring Valley | Spring Valley, IL |
| Illinois | Springerton | Springerton, IL |
| Illinois | Springfield | Springfield, IL |
| Illinois | Standard | Standard, IL |
| Illinois | Stanford | Stanford, IL |
| Illinois | Staunton | Staunton, IL |