Interstate 43

Interstate 43 Wisconsin
Beloit, WI ↔ Howard, WI•191.55 miles•1 Branch Route

Overview

Interstate 43 connects the Milwaukee area with Beloit to the southwest and Green Bay to the north. Following the Rock Freeway, I-43 originates at I-39/90 and angles northeast from Beloit to Delavan, Elkhorn, Mukwonago and the southwestern Milwaukee suburbs. Once at the Hale Interchange with Interstate 41 and I-894 in Greenfield, I-43 joins the Airport Freeway east to south Milwaukee and the Airport Interchange with I-94.

Combining with Interstate 94 (North South Freeway), I-43 turns north through the Saveland Park and Walker's Point neighborhoods of Milwaukee to the Marquette Interchange with the East West Freeway. There I-94 turns west through Menomonee River Valley while I-794 spurs east to Downtown and the Historic Third Ward. Interstate 43 meanwhile remains along the North South Freeway to Kilbourn Town, Harambee and an exit of Milwaukee at Grover Heights.

The urban style freeway of I-43 advances north through Glendale along an expressway originally built for U.S. 141. Continuing through the northern suburb villages of Fox Point, River Hills and Bayside, Interstate 43 leaves the Milwaukee area for Saukville and the split with Wis 57. There the freeway turns east by Port Washington to run along the west shore of Lake Michigan to Sheboygan and Manitowoc.

Leo Frigo Bridge - Green Bay, WI
View of Leo Frigo Bridge from mouth of Fox River. Photo by Peter Johnson (06/17/15).

The rural freeway leads away from the lake through northern Manitowoc County to enter Brown County and the Green Bay metropolitan area. Once at Bellevue, I-43 curves northeast than west as part a belt route with Wis 172 and I-41 encircling Green Bay. The final stretch traverses industrial and wetland areas along the southern periphery of Green Bay itself, including the high level Leo Frigo Bridge across the Fox River.

Mileage by State

Wisconsin187.80 mi

Data Sources

December 31, 2025 Interstate Route Log and Finders List

Parallel U.S. Routes

Interstate 43 replaced U.S. 141 between Milwaukee and Green Bay. The route also doubles as U.S. 41 along the south leg of I-41/894 in Milwaukee.

I-43 southbound on the Leo Frigo Bridge in Green Bay, Wisconsin.
The Leo Frigo Bridge spans the Fox River near its mouth on Green Bay. A portion of the arch bridge sagged on September 25, 2013, leading to a three month plus emergency closure for repairs. WisDOT indicated that soil conditions corroded steel pilings, causing one to buckle and a pier to sink. Measures were taken during the $15 million repair project to prevent corrosion for a 75 year period.5 Photo by Peter Johnson (06/17/15).
I-41/43 interchange by the Ken Euers Nature Area
Looking west from the Ken Euers Nature Area at the interchange between I-41, I-43 and U.S. 41 and U.S. 141. The ramps from I-41 south to I-43 south and I-43 south to I-41 south closed on October 23, 2015. The last phase of the I-41 Project reopened those connections with new ramps in August 2016. Photo by Peter Johnson (10/22/15).

History

Interstate 43 was not an original 1956 Interstate Highway; it was commissioned in the 1970s along U.S. 141 as part of the Milwaukee-Green Bay Interstate Highway.1 Government planning maps of the Interstate Highway System from that era initially showed Interstate 43 as part of an extended Interstate 57, with presumably a long overlap along Interstate 94 from Chicago to Milwaukee (note that this overlap was never shown on any planning maps, so it would have been implied). Potential funding for the freeway in 1972 referenced the future Interstate as an extension of I-57 as well.2

The initial 82 mile long route for I-57 was approved by the Federal Highway Administration in May 1973 from Saukville, northeast along U.S. 141, to Wis 42 at Sheboygan and then northward to U.S. 151 outside Manitowoc. A northwesterly trajectory took I-57 from U.S. 151 to the planned Bellevue interchange south of Green Bay. This route did not extend south of Saukville due to the controversial Cedarburg Bog area. Instead provisions were made to tie the new I-57 in with the preexisting U.S. 141 freeway south of Saukville. The proposed new I-57 took it through Mequon and along the Wisconsin 57 corridor into Milwaukee otherwise.3

Milwaukee, WI - 1962
The initial stretch of what would eventually become a part of Interstate 43 appears on this 1962 map of Milwaukee. The first portion of U.S. 141 upgraded to the North-South Freeway in Milwaukee ran north from Wis 190 (Capitol Drive) to County Trunk Highway PP (Good Hope Road). This stretch was completed in 1963.6
Southeastern Wisconsin - 1975
Interstate 43 debuted on the 1975 edition of the Rand McNally North American Road Atlas. I-43 was posted in 1975 along U.S. 141 from Interstate 94 in Milwaukee to Wis 23 at Sheboygan. U.S. 141 was truncated northward to Grafton by 1977.6

The Milwaukee-Green Bay Interstate was soon designated as a distinct route (numbered Interstate 43) and the southern terminus was located at the current junction between Interstates 94 and 794 (Marquette Interchange) in Downtown Milwaukee. The existing U.S. 141 freeway in north Milwaukee became part of I-43; the Interstate was then extended north toward Green Bay. Construction of this portion of the route was completed in 1981.1

Further south, what was originally designated as Wis 15 (via the Rock Freeway, which connected Beloit with Milwaukee) began construction in 1969 and was completed in 1976. Approximately ten years later on November 24, 1987, the highway was added to Interstate 43. With this action, I-43 gained 72 miles to the southwest along Wis 15 (Rock Freeway) to Interstate 90 near the state line.1 STH-15 was decommissioned by this action. With the extension of Interstate 39 into Wisconsin on October 16, 1992, I-43 connected to I-39. Signs for Interstate 39 were mostly erected around 1996.

For more information, visit Chris Bessert's Wisconsin Highways: Interstate 43 page. This page also includes a discussion of the proposed location of the "Milwaukee to Green Bay Interstate Highway," including consideration for what later became Interstate 41 as a candidate for I-43 in the early planning stages.

Major Projects

Construction at Interstate 41 modernized and expands the freeway through the Green Bay area as part of the overall US 41 Project through Brown County. Work at the north end of Interstate 43 included an upgrade of the substandard cloverleaf interchange into a high-speed directional T interchange. The southbound beginning of I-43 from I-41 shifted from a tight right side ramp to a new directional ramp departing from the left. Work also separated movements at the adjacent diamond interchange with U.S. 141 and County HS (Velp Avenue). Construction commenced in September 2013, with the interchange at I-41 and U.S. 141 opened to traffic on August 26, 2016.

A major revamp of the south end for Interstate 43, where I-39, I-90 and I-94 come together with Wis 81, was part of the long term I-39/90 Expansion Project. Work replaced the cloverleaf interchange there with a directional T interchange joining I-43 with I-39/90/94 and a diverging diamond (DDI) for Beloit via Wis 81. Three projects upgraded I-43:7

North End Interstate 41 U.S. 41 U.S. 141 ‐ Howard, WI

Interstate 43 North at Interstate 41 U.S. 41 U.S. 141

I-43 north at I-41/US 41-141 - Howard, WI

End signage for Interstate 43 was installed during September 2015. Photo by Peter Johnson (02/02/18).

I-43 north Leo Frigo Bridge - Green Bay, WI I-43 north at I-41/US 41-141 - Green Bay, WI I-43 north at I-41/US 41-141 - Green Bay, WI I-43 north at I-41/US 41-141 - Green Bay, WI I-43 north at I-41/US 41-141 - Green Bay, WI I-43 north at I-41/US 41-141 - Howard, WI I-43 north at I-41/US 41-141 - Howard, WI I-43 north at I-41/US 41-141 - Howard, WI

Interstate 41 U.S. 41 U.S. 141 South at Interstate 43

I-41/US 41-141 south at I-43 - Howard, WI

I-41 expands to five southbound lanes auxiliary lanes open for Interstate 43 south. A left exit for I-43 was used because of the wetlands and tight space between the freeway and adjacent Velp Avenue. Milwaukee is the control city because I-43 is a shorter route to Wisconsin’s largest city than I-41 at this point. Photo by Peter Johnson (06/14/18).

I-41/US 41-141 south at I-43 - Howard, WI I-41/US 41-141 south at I-43 - Howard, WI I-41/US 41-141 south at I-43 - Howard, WI I-41/US 41-141 south at I-43 - Howard, WI

Interstate 41 U.S. 41 U.S. 141 North at Interstate 43

I-41/US 41 north at I-43/US 141 - Howard, WI

A dumbbell interchange (Exit 170A) joins U.S. 141 north with I-41 north ahead of the directional T interchange (Exit 170B) with Interstate 43 south. Photo by Peter Johnson (01/30/18).

I-41/US 41 north at I-43/US 141 - Howard, WI I-41/US 41 north at I-43/US 141 - Howard, WI I-41/US 41 north at I-43/US 141 - Howard, WI I-41/US 41 north at I-43/US 141 - Howard, WI

Interstate 43 South

I-43 south at I-41/US 41 - Howard, WI

The first reassurance shield for Interstate 43 south, posted just after the August 28, 2015 opened ramp from I-41 north to I-43 south. Photo by Peter Johnson (01/30/18).

North End – Past Views

Past Views Gallery (Tap to Expand / Collapse Section)

Interstate 43 North at U.S. 41 U.S. 141

I-43 north at US 41/141 - 2000

This scene is now where the southbound flyover to Interstate 41/U.S. 41-141 departs. Photo by Jeff Royston (10/00).

I-43 north at US 41/141 - 2007 I-43 north at US 41/141 - 2007 I-43 north at US 41/141 - 2007 I-43 north at US 41/141 - 2000 I-43 north at US 41/141 - 2009 I-43 north at US 41/141 - 2007 I-43 north at US 41/141 - 2007

U.S. 41 U.S. 141 South at Interstate 43

US 41/141 south at I-43 - 2011

Traffic departed U.S. 41/141 for the southbound beginning of Interstate 43 at Exit 171. The previous exchange between the two freeways was similar to a folded diamond interchange, with low speed ramps. I-41/U.S. 41 connects Green Bay with the Fox Valley Cities of Appleton and Oshkosh while I-43 heads southeast to Sheboygan and Manitowoc. 05/30/11

US 41/141 south at I-43 - 2011 US 41/141 south at I-43 - 2011

U.S. 41 U.S. 141 North at Interstate 43

US 41/141 north at I-43 - 2011

Traveling north on U.S. 41 across Velp Avenue, a half mile ahead of the previous interchange (Exit 171) connecting with Interstate 43 south. I-43 serves Downtown Green Bay before reaching Wis 54 and Wis 57, which provide a direct link to Door County. Otherwise, Interstate 43 turns to the south towards Sheboygan and Milwaukee. 05/30/11

US 41/141 north at I-43 - 2011 US 41/141 north at I-43 - 2011

South End Interstate 39 Interstate 90 Wisconsin Trunk Highway 81 ‐ Beloit, WI

Interstate 43 South at Interstate 39 Interstate 90 Wisconsin Trunk Highway 81

I-43 south at I-39/90 - Beloit, WI

Previous guide signs for Exit 1B used Madison in place of Janesville for I-39/90 north. Rockford, Illinois was added for Exit 1 A. Photo by Peter Johnson (12/27/21).

I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - 2002

Interstate 39 North Interstate 90 West at Interstate 43 Wisconsin Trunk Highway 81

I-39/90 north at I-43/Wis 81 - Beloit, WI

Cranston Road spans I-39/90 north southeast from an area of industrial businesses south of Wis 81 (Milwaukee Road) just ahead of the DDI at Exit 185 A. Photo by Peter Johnson (12/17/21).

I-39/90 north at I-43/Wis 81 - Beloit, WI I-39/90 north at I-43/Wis 81 - Beloit, WI I-39/90 north at I-43/Wis 81 - Beloit, WI I-39/90 north at I-43/Wis 81 - Beloit, WI I-39/90 north at I-43/Wis 81 - Beloit, WI Wis 81 east at I-43 - Beloit, WI

Interstate 39 South Interstate 90 East at Interstate 43 Wisconsin Trunk Highway 81

I-39/90 south at I-43/Wis 81 - Beloit, WI

I-39/90 continue south from STH-S (Shopiere Road) to Exits 185 A/B for Interstate 43 north and Wis 81 (Milwaukee Road) west. Photo by Peter Johnson (12/17/21).

I-39/90 south at I-43/Wis 81 - Beloit, WI I-39/90 south at I-43/Wis 81 - Beloit, WI I-39/90 south at I-43/Wis 81 - Beloit, WI

South End – Past Views

Past Views Gallery (Tap to Expand / Collapse Section)

Interstate 43 South at Interstate 39 Interstate 90 Wisconsin Trunk Highway 81

I-43 south at I-39/90 - 2010

An end shield precedes the ramp departures for I-39/90 and the I-43 transition into Wis 81, a commercial arterial extending west into Beloit. 05/06/10

I-43 south at I-39/90 - 2011 I-43 south at I-39/90 - 2010 I-43 south at I-39/90 - 2007 I-43 south at I-39/90 - 2010 I-43 south at I-39/90 - 2010 I-43 south at I-39/90 - 2010

Interstate 43 South at Interstate 39 Interstate 90 Wisconsin Trunk Highway 81

I-43 south at I-39/90 - Beloit, WI

Interstate 43 south at I-39/90 and Wis 81 west during construction of the I-39/90 and I-43/WIS 81 Interchange project. Photo by Peter Johnson (04/10/20).

I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI I-43 south at I-39/90 - Beloit, WI

Wisconsin Trunk Highway 81 East at Interstate 43 Interstate 39 Interstate 90

WIS 81 east at I-39/43/90 - 2010

Wis 81 end shield assembly posted ahead of the arterial transition into Interstate 43. A signalized intersection lies ahead with Ford Drive north and Freeman Parkway south, local roads serving adjacent businesses and subdivisions. 05/06/10

WIS 81 east at I-39/43/90 - 2007 WIS 81 east at I-39/43/90 - 2010 WIS 81 east at I-39/43/90 - 2010 WIS 81 east at I-39/43/90 - 2010

Interstate 43 North at Interstate 39 Interstate 90

I-43 north at CTH-X - Beloit, WI

Millington Road forms a south side frontage road to Interstate 43 as motorists pass by the first northbound reassurance marker. The freeway doubles as an Alternate route for I-39 to Exit 6 with Wis 140. 05/06/10

WIS 81 east at I-39/43/90 - 2010 I-43 north at CTH-X - Beloit, WI I-43 north at I-39/90 - Beloit, WI I-43 north at I-39/90 - Beloit, WI I-43 north at I-39/90 - Beloit, WI I-43 north at I-39/90 - Beloit, WI I-43 north at CTH X - Beloit, WI

Interstate 39 North Interstate 90 West at Interstate 43 Wisconsin Trunk Highway 81

I-39/90 north at I-43/WIS 81 - 2010

The northbound beginning of Interstate 43 departs I-39 north / I-90 west via Exit 185B. I-43 serves the cities of Delavan, Elkhorn, and Waukesha on its northeasterly course toward Milwaukee. The freeway reaches I-41/894 in 60 miles. 05/06/10

I-39/90 north at I-43/WIS 81 - 2010 I-39/90 north at I-43/WIS 81 - 2010 I-39/90 north at I-43/WIS 81 - 2010

Interstate 39 South Interstate 90 East at Interstate 43 Wisconsin Trunk Highway 81

I-39/90 south at I-43/WIS 81 - 2010

Exit 185A departs I-39 south / I-90 west for Wis 81 (Milwaukee Road) west. The Trunk Highway extends west from the ending I-43 toward Downtown Beloit to the straddle southern reaches of Wisconsin westward to Cassville along the Mississippi River. 05/06/10

I-39/90 south at I-43/WIS 81 - 2010 I-39/90 south at I-43/WIS 81 - 2010 I-39/90 south at I-43/WIS 81 - 2010

References

  1. Wisconsin Highways: Highways 40-49, Chris Bessert. Retrieved from http://www.wisconsinhighways.org/listings/WiscHwys40-49.html#I-043
  2. "I-57 Fund Extension Appears Probable." The Milwaukee Journal, October 7, 1972.
  3. "Route Approved for I-57." The Milwaukee Journal, May 18, 1973.
  4. State of Wisconsin Statutes: Chapter 84, State Trunk Highways (Federal Aid) - Section 84.1033 states as follows: "Leo Frigo Memorial Bridge. No later than 6 months after May 9, 2002, the department shall designate and mark the bridge on I 43 across the Fox River in the city of Green Bay as the "Leo Frigo Memorial Bridge" in recognition and appreciation of Leo Frigo, a civic and philanthropic leader in the Green Bay area whose legacy includes one of the largest food pantry programs in the nation for feeding the hungry." Retrieved from https://docs.legis.wisconsin.gov/statutes/statutes/84.pdf
  5. "Final investigative report from Leo Frigo Bridge sagging released." Fox 11 News, May 18, 2015.
  6. Wisconsin Highways: Highways 140-149, Chris Bessert. Retrieved from http://www.wisconsinhighways.org/listings/WiscHwys140-149.html#US-141
  7. I-39/90 Expansion Project, Project Overview. https://projects.511wi.gov/i-39-90/full-project-overview/ Wisconsin Department of Transportation.
Updated May 23, 2022