Towns
| State | City/Town | Town Title |
|---|---|---|
| Illinois | Seneca | Seneca, IL |
| Illinois | Serena | Serena, IL |
| Illinois | Sesser | Sesser, IL |
| Illinois | Seward | Seward, IL |
| Illinois | Seymour | Seymour, IL |
| Illinois | Shabbona | Shabbona, IL |
| Illinois | Shannon | Shannon, IL |
| Illinois | Shawneetown | Shawneetown, IL |
| Illinois | Sheffield | Sheffield, IL |
| Illinois | Shelbyville | Shelbyville, IL |
| Illinois | Sheldon | Sheldon, IL |
| Illinois | Sheridan | Sheridan, IL |
| Illinois | Sherman | Sherman, IL |
| Illinois | Sherrard | Sherrard, IL |
| Illinois | Shipman | Shipman, IL |
| Illinois | Shirland | Shirland, IL |
| Illinois | Shirley | Shirley, IL |
| Illinois | Shobonier | Shobonier, IL |
| Illinois | Shorewood | Shorewood, IL |
| Illinois | Shumway | Shumway, IL |
| Illinois | Sibley | Sibley, IL |
| Illinois | Sidell | Sidell, IL |
| Illinois | Sidney | Sidney, IL |
| Illinois | Sigel | Sigel, IL |
| Illinois | Silvis | Silvis, IL |