Its eastern terminus is at U.S. Route 45 (US 45) at Onarga, one mile (1.6 km) east of I-57.

[1] IL 54 runs southwest-to-northeast from Springfield.

It is now mainly a local road, as I-55 and I-57 have become preferred for long distance travel in the region.

US 54 now terminates between Pittsfield and Griggsville at mile marker 35 on I-72/US 36.

The US 54 alignment between this point and IL 54's current western terminus has since been replaced by the combined I-72/US 36 freeway and I-55.