It runs from U.S. Route 34 (US 34) in La Moille southward to IL 116 in Metamora.

[1] Starting at La Moille, IL 89 travels south and passes through the small towns of Arlington, Cherry, and Ladd, where it crosses I-80.

After passing Spring Valley and crossing the Illinois River, IL 89 crosses IL 71 near Granville, then passes through McNabb.

It was truncated north at Granville in 1938 and rerouted to La Moille.

The highway's crossing of the Illinois River in Spring Valley was replaced with a new bridge that opened on June 18, 2018.