Towns
| State | City/Town | Town Title |
|---|---|---|
| Illinois | Iroquois | Iroquois, IL |
| Illinois | Irving | Irving, IL |
| Illinois | Irvington | Irvington, IL |
| Illinois | Island Lake | Island Lake, IL |
| Illinois | Itasca | Itasca, IL |
| Illinois | Iuka | Iuka, IL |
| Illinois | Ivesdale | Ivesdale, IL |
| Illinois | Jacksonville | Jacksonville, IL |
| Illinois | Jacob | Jacob, IL |
| Illinois | Janesville | Janesville, IL |
| Illinois | Jerseyville | Jerseyville, IL |
| Illinois | Jewett | Jewett, IL |
| Illinois | Johnsonville | Johnsonville, IL |
| Illinois | Johnston City | Johnston City, IL |
| Illinois | Joliet | Joliet, IL |
| Illinois | Jonesboro | Jonesboro, IL |
| Illinois | Joppa | Joppa, IL |
| Illinois | Joy | Joy, IL |
| Illinois | Junction | Junction, IL |
| Illinois | Justice | Justice, IL |
| Illinois | Kampsville | Kampsville, IL |
| Illinois | Kane | Kane, IL |
| Illinois | Kaneville | Kaneville, IL |
| Illinois | Kankakee | Kankakee, IL |
| Illinois | Kansas | Kansas, IL |