The route is a short connector that bridges the city of Whitewater and points west via U.S. Highway 12 (US 12) with East Troy, Waterford and Racine.

WIS 20 begins at the junction of US 12 and WIS 67 and proceeds east, going south around a junction with County Trunk Highway J (CTH-J) 1+1⁄2 miles (2.4 km) east of the terminus and bypassing the small community of Troy Center.

The two routes follow Washington Avenue northeast and turn east onto the one-way 7th Street.

[7] The section between Rochester and Racine existed since the dawn of the Wisconsin highway system in 1917.

[8] The route was scaled back to end at Rochester in 1934 when US 14 replaced WIS 11's original alignment.