About double that time or more. Illinois is a long state north to south.
It was to Louisville not St Louis. Straight down 65.
To be perfectly accurate 5 hrs 8 min at the speed limit.
https://www.google.com/maps/dir/chicago+o’hare/louisville/@40.0960296,-89.0737993,7z/data=!3m1!4b1!4m13!4m12!1m5!1m1!1s0x880fb4276a7762f3:0x511747070259ad4b!2m2!1d-87.9073214!2d41.9741625!1m5!1m1!1s0x88690b1ab35bd511:0xd4d3b4282071fd32!2m2!1d-85.7584557!2d38.2526647