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Wisconsin Highway 78

State Trunk Highway 78 (often called Highway 78, STH 78 or WIS 78) is a state highway in the U.S. state of Wisconsin. It runs north–south in south central Wisconsin from Portage to the Illinois border near Gratiot.

State Trunk Highway 78 marker

State Trunk Highway 78
Route information
Maintained by WisDOT
Length92.83 mi[1] (149.40 km)
Major junctions
South end IL 78 in Gratiot
  US 18 / US 151 in Mt. Horeb
US 14 in Black Earth
US 14 / WIS 19 in Mazomanie
US 12 / WIS 60 in Sauk City
North end I-39 / I-90 / I-94 in Portage
CountiesLafayette, Iowa, Green, Dane, Sauk, Columbia
Highway system
WIS 77WIS 79

Historical note: In the 1920s, Highway 78 was originally located on the Door County Peninsula on what is now Highway 57.


  1. ^ Bessert, Chris. "Wisconsin Highways: Highways 70-79 (Highway 78)". Wisconsin Highways. Retrieved 2007-03-20.