 US 12/US 18 was upgraded to expressway standards between I-39/I-90 to North Star Road, west of Cambridge.The remainder wasn't expanded, but straightened out to eliminate sharp curves.In 2019, as part of the construction to complete the Waukesha Bypass, US 18 has been rerouted as Temporary US 18 from WIS 83 in Wales, north along WIS 83 to I-94 and east along I-94 to exit 297 at Blue Mound Road where it rejoins the previous route.