In the state of Illinois, Interstate 39 runs from Interstate 55 north of the Bloomington-Normal, Illinois area alongside of Illinois 251. Interstate 39 joins I-90 near Rockford in the town of Cherry Valley and continues north to the Wisconsin state line as part of the Jane Addams Memorial Tollway. The only toll booth is located at South Beloit where $1.00 is collected from every automobile. ($.50 for those with I-Pass transponders).
I-39 enters Wisconsin with I-90 near Beloit and heads north. At Madison, I-39/90 is joined by I-94. I-39/90/94 from Madison to just south of Portage is the longest three-Interstate concurrency in the United States. I-39 departs at Portage heading north, almost entirely with U.S. Highway 51 and crosses I-43/ WI Hwy.29 at Wausau. I-39 ends just north of it's intersection with U.S. Highway 8, west of Rhinelander, WI. U.S. 51 then continues north as a 2 or 3 lane road to Hurley/Ironwood, at the Michigan State Line.