Wisconsin Highway 81

State Trunk Highway 81
WIS 81 highlighted in red
Route information
Maintained by WisDOT
Length	123.81 mi[1] (199.25 km)
Major junctions
West end	WIS 133 in Cassville
Major intersections	US 61 / WIS 35 in Lancaster US 151 in Platteville US 51 in Beloit I-39 / I-90 in Beloit
East end	I-43 in Beloit
Location
Country	United States
State	Wisconsin
Counties	Grant, Lafayette, Green, Rock
Highway system
Wisconsin State Trunk Highway System Interstate US State Scenic Rustic
← WIS 80 → WIS 82

State Trunk Highway 81 (often called Highway 81, STH-81 or WIS 81) is a state highway in the U.S. state of Wisconsin. It runs east–west in southwest and south central Wisconsin from Cassville to Beloit. Between Brodhead and Monroe it run concurrently with WIS 11 for 13 miles (21 km). The route was originally designated as a state highway in the early 1920s, but there were three different designations along the route. It was not signed as WIS 81 along the entire route until 1934.