A total of three business routes of U.S. Highway 12 (US 12) currently exist in Wisconsin.

Business routes typically run through cities, after a highway was realigned.

None are official state highways according to the Wisconsin Department of Transportation (WisDOT) and are thus locally maintained.

Between the mid-1940s to 1964, Wisconsin Highway 172 (WIS 172) served as the business route of US 12 in Eau Claire.

[5][6] Within a year after the formation, WIS 172 was decommissioned in favor of the new business route.

[10] It is cosigned as County Trunk Highway BD (CTH-BD); extending until West Baraboo.

[16][17] Around the early 1970s, all of Madison's business routes (except for the already-decommissioned Bus.