It runs from Illinois Route 116 just north of East Peoria to Highway 69 at the Wisconsin border near Orangeville.

Its southern terminus is just one mile (1.6 km) north of the McClugage Bridge carrying U.S. Route 150 into Peoria.

SBI Route 26 originally ran from Freeport to Polo, on part of current IL-26.

In northern Stephenson County, IL 26 originally ran through downtown Orangeville and the unincorporated community of Oneco.

[citation needed] the old approaches are now local roads, used mainly as access to riverside industries on both banks.