U.S. Route 51 is a south-north United States highway that runs for from the western suburbs of New Orleans, Louisiana to within of the Wisconsin–Michigan border. Much of the highway in Illinois and southern Wisconsin runs parallel to or overlaps Interstate 39 (I-39), and much of the route in several states also parallels the Illinois Central Railroad. The highway's northern terminus is between Hurley, Wisconsin, and Ironwood, Michigan, where it ends with a T interchange at US 2. Its southern terminus is Laplace, Louisiana, ending at US 61.