^Looking west as Illinois 75 leaves Rockton, February 2021.
Illinois Route 75 runs southwest-northeast in the center of far northern Illinois. It runs from Freeport northeast through several towns, ending in South Beloit, where it becomes Wisconsin Highway 67 at a state border crossing.
The western end of Illinois 75 is at Illinois 26 in the heart of Freeport:
Several blocks to the east, Illinois 75 crosses the BusinessUS Route 20 alignment for Freeport:
Just south of the Wisconsin border, Illinois 75 splits from Illinois 2 to head east:
In South Beloit, Illinois 75 meets the point where US Route 51 comes from Beloit and turns easterly to form a concurrency, and the southern leg of the intersection is the northern extent of Illinois 251:
As US Route 51 and Illinois 75 approach Interstates 39 and 90 together, US Route 51 joins the expressway south, leaving Illinois 75 to continue eastward:
Soon after passing Interstates 39 and 90, Illinois 75 curves northward to end at the Wisconsin border, where it becomes Wisconsin Highway 67: