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 Interstates 41 and 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.
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.
A major revamp of the southern terminus, where I-39, I-90 and I-94 come together with Wis 81, is underway as part of the long term I-39/90 Expansion Project. Work replaces the cloverleaf interchange with a semi directional T interchange for interstate traffic and a diverging diamond (DDI) for Beloit via Wis 81. Three projects effect I-43:
- 1003-10-79 – I-43 Interchange Off Alignment – Summer 2018 to Fall 2019.
- 1003-10-80 – I-43 Interchange and Mainline Reconstruction – Summer 2019 to Fall 2021.
- 1003-11-71 – I-39/90 and I-43 Mainline Reconstruction – Summer 2018 to Fall 2019.
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.
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 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
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.
North End – Howard, WI
South End – Beloit, WI
Branch Routes – 0
Mileage – 191.55*
Cities – Beloit, Delavan, Milwaukee, Sheboygan, Manitowoc, Green Bay
- Junctions –
Source: December 31, 2018 Interstate Route Log and Finders List
* – 5 miles on I-41
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
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.
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
Interstate 43 was posted in 1975 along the U.S. 141 freeway from Interstate 94 in Milwaukee to Wis 23 at Sheboygan. U.S. 141 was truncated northward to Grafton by 1977.6
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.
North End – Howard, Wisconsin
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).
The high-speed ramp to Interstate 43 south does not have any advisory speed so traffic can safely exit at 70 miles per hour. Interstate 43 forms the north and east legs of the Green Bay Beltway. U.S. 141 departs I-41 at the succeeding ramp to the right and joins Velp Avenue east toward Downtown Green Bay. Photo by Peter Johnson (06/14/18).
Interstate 41 turns northeasterly from Green Bay into the village of Howard on the approach to U.S. 141 and CTH-HS (Velp Avenue) and I-43 south. Completed in December 2016, the systems interchange at Exit 170 utilizes a distributor roadway northbound for both Velp Avenue and Interstate 43 south. Photo by Peter Johnson (06/14/18).
North End Throwback
Sign bridge located by the Military Avenue overpass on I-43 north. One lane was allocated for each direction of U.S. 41-141. U.S. 141 south was omitted from overhead for Exit 192B, due to U.S. 141 south exiting almost immediately after Interstate 43’s northern terminus. Photo by Chris Lokken and Sage Sulenta (04/14/07).
One mile north of Interstate 43 south along U.S. 41-141 southbound. Interstate 43 serves the immediate waterfront area of Green Bay before encircling the east side, while I-41/U.S. 41 stays on the west side of the city. 05/30/11
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
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
This sign bridge was located at the split of traffic between U.S. 41/141 north and Interstate 43 south. U.S. 41 and U.S. 141 extended north along a freeway from Howard to Abrams before separating to Marinette and Iron Mountain, Michigan respectively. This loop ramp was replaced by a new directional ramp during road work between 2013-16. 05/30/11
South End – Beloit, Wisconsin
Interstate 43 south at I-39/90 and Wis 81 west. Photos by Peter Johnson (04/10/20).
Stage 2A Phase 1 of the I-39/90 & I-43/WIS 81 Interchange project removed the loop ramps between the two freeways and converted the exchange into a diamond interchange temporarily.
A loop ramp will connect I-43 south and Wis 81 east to I-39/90 southbound during Stage 2B Phase 2 in Fall 2020.
Wis 81 east transitions into Interstate 43 northbound through the temporary diamond interchange with I-39/90 north to Janesville and Madison and I-39/90 south to Rockford, Illinois. Photo taken by Peter Johnson (04/10/20).
Flyovers will join I-39/90 with Interstate 43 above a diverging diamond interchange (DDI) being built with Wis 81 below. Wis 81 will be extended east over Gateway Boulevard to the dumbbell interchange (Exit 2) joining Hart Road (CTH-X) with I-43. Completion of the final interchange layout is scheduled for Fall 2021.
South End Throwback
North West at
South East at
- Wisconsin Highways: Highways 40-49, Chris Bessert.
- “I-57 Fund Extension Appears Probable.” The Milwaukee Journal, October 7, 1972.
- “Route Approved for I-57.” The Milwaukee Journal, May 18, 1973.
- 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.”
- “Final investigative report from Leo Frigo Bridge sagging released.” Fox 11 News, May 18, 2015.
- Wisconsin Highways: Highways 140-149, Chris Bessert.
Page updated May 6, 2020.