State Trunk Highway 113 (often called Highway 113, STH-113 or WIS 113) is a state highway in the U.S. state of Wisconsin. It runs in north–south in south central Wisconsin from Madison to Baraboo, The highway uses the Merrimac Ferry, the last ferry in the Wisconsin state highway system, to cross the Wisconsin River at Merrimac. Over the length of the road, it runs through Dane, Columbia, and Sauk counties.