 The route was truncated on the southern end to end at Janesville in the late 1940s.Four bypasses were constructed for WIS 26 - around Milton to the east in 2013-14, around Fort Atkinson to the west in the 1990s, around Jefferson to the west in the 2000s, and around Watertown to the west in 2012-14.

Business WIS 26 in Fort Atkinson starts at WIS 26 Exit 17 and follows Janesville Ave., Robert St., Madison Ave., North 3rd St., and N. High St. before ending at WIS 26 Exit 23.

Business WIS 26 in Jefferson starts at WIS 26 Exit 25 and follows the old routing of WIS 26 along Main St before ending at WIS 26 Exit 30.

Business WIS 26 in Watertown starts at WIS 26 Exit 39 and follows the old routing of WIS 26 along Church St. to Wisconsin 16.It then turns west with WIS 16 for a short distance before ending at WIS 26 Exit 45.