^Westbound trailblazer at Illinois 130 outside Olney, October 2019.
In Illinois, US Route 50 runs east-west across the southern part of the state. It enters the state of Illinois crossing the Mississippi River just south of St. Louis, and then it runs along a corridor between Interstates 64 and 70, departing from Illinois into Vincennes, Indiana.
US Route 50's western entrance into Illinois is along the bridge carrying Interstate 255 around the south side of the St. Louis metropolitan area:
Exit 19B from Interstate 64 occurs at a cloverleaf interchange, where O'Fallon meets Shiloh, and where the northern end of Illinois 158 meets the start of US Route 50's existence as an independent surface highway:
In Lebanon, US Route 50 joins Illinois 4 north for about a mile...
In downtown Lebanon, US Route 50 splits from Illinois 4 to head east:
US Route 50 has a bit of an expressway section, and it creates a diamond interchange with Illinois 160 in Trenton, Illinois...