^Northbound trailblazer as Illinois 73 gets its start in Lanark at US Route 52, September 2024.
Illinois Route 73 runs north-south in northwestern Illinois. It connects various small towns in Carroll and Stephenson Counties.
The northern end of Illinois 73 is the Wisconsin border, just outside of Winslow, but continuing north of the border will only put you on a county route known as County Highway M: