| State: | IL |
| Type: | IL |
| Maint: | IDOT |
| Route: | 135 |
| Map Custom: | yes |
| Map Notes: | IL 135 highlighted in red |
| Length Mi: | 20.31 |
| Length Round: | 2 |
| Length Ref: | [1] |
| Established: | March 1937[2] |
| Direction A: | CCW |
| Terminus A: | in Kirkwood |
| Junction: | in Alexis |
| Direction B: | CW |
| Terminus B: | Main Street in Alexis |
| Counties: | Warren, Mercer |
| Previous Route: | 134 |
| Previous Type: | IL |
| Next Route: | 136 |
| Next Type: | US |
Illinois Route 135 (IL 135) is a 20.31miles, L-shaped state road in Warren County, Illinois, United States, that runs from IL 164 west of Monmouth to Main Street in Alexis, at the base of the town's water tower.[1]
IL 135 is an undivided two-lane surface road for its entire length. It runs concurrently with IL 94 for a few miles north of Little York, and with U.S. Route 67 (US 67) for a few miles west of Alexis. IL 135 is signed in all four directions and changes directions at the turnoff from IL 94.
SBI Route 135 originally ran from IL 1 to State Road 154 (SR 154) near Hutsonville via a bridge over the Wabash River. This was removed in 1935; the bridge is now unnumbered. In 1937 it was applied on what was IL 94B, the current routing.