Interstate 39 (I-39) is an Interstate Highway in the midwestern United States. Its southern terminus is in Normal, Illinois, at an interchange with Interstate 55; its northern terminus is at an exit with U.S. Route 51 and Wisconsin State Road 29 near Wausau, Wisconsin. The route runs through the major cities of Normal, Illinois, La Salle-Peru, Illinois, Rockford, Illinois, Beloit, Wisconsin, Janesville, Wisconsin, Madison, Wisconsin, Portage, Wisconsin, Steven's Point, Wisconsin, and Wausau, Wisconsin.