Wisconsin Highway 81

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State Trunk Highway 81

WIS 81 highlighted in red
Route information
Maintained by WisDOT
Length123.81 mi[1] (199.25 km)
Major junctions
West end WIS 133 in Cassville
Major intersections
East end I-43 in Beloit
CountryUnited States
CountiesGrant, Lafayette, Green, Rock
Highway system
WIS 80 WIS 82

State Trunk Highway 81 (often called Highway 81, STH-81 or WIS 81) is a state highway in the U.S. state of Wisconsin. It runs east–west in southwest and south central Wisconsin from Cassville to Beloit. Between Brodhead and Monroe it run concurrently with WIS 11 for 13 miles (21 km). The route was originally designated as a state highway in the early 1920s, but there were three different designations along the route. It was not signed as WIS 81 along the entire route until 1934.

Junction at Brodhead with WIS 11 and CTH-GG

Route description

The highway begins at an intersection with WIS 133 in Cassville, a village along the Mississippi River bordering Iowa, and runs northeastward from it. It intersects County Trunk Highway U (CTH-U) in Beetown and then runs concurrently with WIS 33 along the Grant River west of Five Points. From there, it continues running northeast, intersecting with CTH-N before reaching Lancaster, where it starts running concurrently with US Highway 61 (US 61). It then runs southeastward, meeting WIS 129, an eastern bypass of Lancaster, before exiting its concurrencies with US 61 and WIS 33. From there. it continues running southeast, passing the community of Ellenboro and running concurrently with CTH-D before entering Platteville along Lancaster Street. The highway then runs along a few of the streets in Platteville and ends its concurrency with CTH-D before starting another concurrency with WIS 80.[2]

The highway runs southeasterly along the WIS 80 concurrency, intersecting with Business US 151 (Bus. US 151) before passing through an interchange with US 151. It then curves to the south, passing by Platteville Municipal Airport before exiting its concurrency with WIS 80 and running east from it. The highway runs directly eastward, passing by Elk Grove and intersecting with WIS 126 and numerous county trunk highways before running along a short concurrency with WIS 23 in Darlington. From there, it runs along the Pecatonica River before it runs south of the highway, and the highway runs east, passing through the community of Lamont before running along a short concurrency with WIS 78 in Argyle.[2]

East of Argyle, the highway runs southeasterly towards Monroe before running concurrently with WIS 11 along a bypass alignment just north of Monroe. The concurrency runs east, passing by Juda before the highway leaves the concurrency and runs southeast from it. The highway curves east in Newark before entering Beloit along Liberty Avenue. West of the Rock River, the highway follows a short concurrency with WIS 213. After crossing the Rock River, the highway intersects US 51 before running northeast from it and terminating at an interchange with Interstate 39/Interstate 90 (I-39/I-90) and continuing as I-43.[2]


The route first appeared as a state trunk highway in the early 1920s but was split into three differently designated segments: from Cassville to the beginning of the WIS 35 (then WIS 65) concurrency, it was WIS 105; from the beginning of said concurrency to Monroe, it was part of WIS 65; and from the end of the WIS 11 (then WIS 20), it was part of WIS 61.[3] In 1924, the entire route was signed as a western extension of WIS 61.[4] In 1927, the highway, along with the rest of WIS 61, had been renumbered to WIS 14.[5] In 1934, when US 14 was designated within the state, the entire route was renumbered to WIS 81.[6] Between 1948 and 1956, the entire route within Grant County was paved. The sections which were not paved in 1956 were the entire route in Lafayette County, between the WIS 11 concurrency and Newark, and a short section along the WIS 11 concurrency near Juda.[7][8]

In 2021, the eastern terminus of the highway was extended to I-43's exit 1 (CTH-X) and the interchange at I-39/90 was changed to a diverging diamond interchange. I-43 now terminates at a directional-T interchange at I-39/90, and the eastern terminus at I-43 is now a dumbbell interchange.

Major junctions

GrantCassville0.00.0 WIS 133 / Great River Road – Nelson Dewey State Park, Stonefield Historic Site
WIS 35 north – Prairie du Chien
Western end of WIS 35 concurrency
US 61 north (Madison Street)
Northern end of US 61 concurrency
South Lancaster20.833.5

Truck US 61 north / WIS 129 north – Fennimore

US 61 south / WIS 35 south – Dickeyville, Dubuque
Southern end of US 61/WIS 35 concurrency
WIS 80 north – Livingston, Montfort
Northern end of WIS 80 concurrency
PlattevillePlatteville (town) line36.558.7 US 151 – Madison, DubuqueInterchange
WIS 80 south – Cuba City, Hazel Green
Southern end of WIS 80 concurrency
LafayetteElk Grove45.673.4
WIS 126 north – Belmont
DarlingtonDarlington (town) line55.889.8
WIS 23 south – Shullsburg
Southern end of WIS 23 concurrency
WIS 23 north (Main Street)
Northern end of WIS 23 concurrency
WIS 78 south – Gratiot
Western end of WIS 78 concurrency
WIS 78 north – Blanchardville
Eastern end of WIS 78 concurrency
GreenTown of Monroe85.7137.9

WIS 11 west / WIS 69 south – Dubuque, Freeport
Western end of WIS 11/WIS 69 concurrency; interchange

WIS 69 north / Bus. WIS 11 – Verona
Eastern end of WIS 69 concurrency; interchange
Monroe (town)Monroe line87.7141.1
WIS 59 east – Albany
Spring Grove99.5160.1

WIS 11 east / CTH-GG north – Brodhead
Eastern end of WIS 11 concurrency
WIS 213 north – Orfordville
Western end of WIS 213 concurrency
WIS 213 south (4th Street)
Eastern end of WIS 213 concurrency
120.0193.1 US 51 (Riverside Drive, Pleasant Street)
I-39 / I-90 / Alt. I-43 – Madison, Chicago
I-39/I-90 exit 185; diverging diamond interchange
CTH-X east
Western end of CTH-X concurrency

I-43 / Alt. I-39 / CTH-X east / Hart Road – Milwaukee, Beloit
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ Bessert, Chris. "Highways 80–89". Wisconsin Highways. Retrieved March 20, 2007.
  2. ^ a b c d Google (April 10, 2020). "Length and Route of WIS 81" (Map). Google Maps. Google. Retrieved April 10, 2020.
  3. ^ Wisconsin State Conservation Commission (c. 1921). Map of the State Highway System of Wisconsin, Showing, Within Red Circle, Location of Northern Lakes Park (Map). Scale not given. n.p.: Wisconsin State Conservation Commission. OCLC 708376740. Retrieved April 11, 2020 – via Wisconsin Historical Society.
  4. ^ Wisconsin Motorists Association (1924). Our Map of Wisconsin (Map). Scale not given. Milwaukee: Wisconsin Motorists Association. OCLC 664274042. Retrieved April 11, 2020 – via Wisconsin Historical Society.
  5. ^ Wisconsin State Highway Commission (1927). Official Highway Map of Wisconsin: 'The Playground of the Middle West' (Map). 1:950,400. Madison: Wisconsin State Highway Commission. OCLC 671337231. Retrieved April 11, 2020 – via Wisconsin Historical Society.
  6. ^ Wisconsin State Highway Commission (1934). Official Highway Map of Wisconsin 1934 (Map). 1:823,680. Madison: Wisconsin State Highway Commission. OCLC 227048467. Retrieved April 11, 2020 – via Wisconsin Historical Society.
  7. ^ Wisconsin State Highway Commission (1948). Preliminary Traffic Map, Showing Annual 24 Hour Average Traffic, State of Wisconsin (Map). c. 1:1,198,000. Madison: Wisconsin State Highway Commission. OCLC 770711221. Retrieved April 11, 2020 – via Wisconsin Historical Society.
  8. ^ Wisconsin Highway Commission (1956). "Wisconsin State Atlas 1956 Highway Maps". Madison: Wisconsin Highway Commission. Retrieved April 11, 2020 – via Historic Map Works.