From there, it runs eastward, following Copper Creek until it ends just west of Mount Sterling, where it intersects WIS 27.

The highway then runs eastward before curving to the north to run along an unnamed creek, which the highway follows to the southeast until it drains into the Kickapoo River, at which point the highway crosses it to run along Main Street in Gays Mills.

After that tributary ends, the highway intersects with County Trunk Highway (CTH) UU and then curves southeast to another unnamed creek which begins near CTH-F.

The highway follows it until reaching CTH-E in Boaz where it runs northward along Mill Creek before terminating at US 14.

[3] By 1925, the construction on the western extension was complete and the WIS 131 designation was extended north to Soldiers Grove.