The route traveled in a southeast–northwest direction from US 45/WIS 55 to WIS 74 in Menomonee Falls (now just Main Street).

After 2.1 miles (3.4 km), the route ended at WIS 74 (Main Street) in Menomonee Falls.

[3] About a year after the realignment, WIS 166 was formed along the southern part of the same former alignment, located south of Menomonee Falls.

[4] WIS 166 was removed in 1953 after US 41 moved north along a newly built divided highway, which was situated just north of WIS 166.

[5][6] The entire route is in Menomonee Falls.