Interstate 43 (I-43): Beloit to Green Bay Route, Length and Crash Record

How long is I-43?

The FHWA Route Log gives I-43 187.80 miles as of January 2026. Both Wikipedia and Interstate Guide list 191.55 miles, and Interstate Guide prints the Route Log's 187.80 in its own state table without explaining why the two figures differ.

The Route Log's notes do not account for the 3.75-mile gap either. I-43's row records 5 miles shared with I-41 on the Airport Freeway between the Hale and Mitchell interchanges, and since I-41's Wisconsin row is the shorter one, this site treats those miles as part of I-43's 187.80. The stretch I-43 shares with I-94 from the Mitchell Interchange to the Marquette Interchange is not noted on either route's row. The crash rate on this page uses the full 187.80 miles.

Where I-43 starts and ends

I-43 begins just east of Beloit at an interchange with I-39 and I-90, which share the road there; west of the junction the pavement continues into Beloit as WIS 81. The northern end is at I-41, US 41 and US 141 in Howard, on the edge of Green Bay in Brown County.

From Beloit the freeway heads northeast through Rock and Walworth counties, passing the Delavan area, Elkhorn and East Troy, then Mukwonago and New Berlin. The Beloit to Milwaukee leg is known as the Rock Freeway, for Rock County and the Rock River valley, though Wikipedia says the name is mostly used in Waukesha and Milwaukee counties. After its run through Milwaukee it goes north through Glendale, Mequon and Grafton, picks up the Lake Michigan shore past Port Washington, Sheboygan and Manitowoc, and cuts northwest through Denmark and Bellevue to Green Bay.

Interstate junctions along I-43

Read from Beloit to Green Bay, the list has four other main Interstates. I-90 and I-39 come first, at one interchange on the south end. I-41 shows up twice. I-43 joins it and I-894 at the Hale Interchange in Greenfield and runs east with them on the Airport Freeway, then meets I-41 again at its northern end in Howard. I-94 comes in at the Mitchell Interchange near the airport, and the two share the North-South Freeway into downtown Milwaukee, where I-43 leaves I-94 at the Marquette Interchange, which also links to I-794, and heads north.

Fatal crashes on I-43

Fatal crashes on I-43 killed 47 people from 2020 through 2024, in 39 separate crashes, or roughly 9 deaths a year. That comes to 5.0 deaths per 100 route miles a year, about half the Interstate average of 9.5. Of 56 Interstates long enough to rate, I-43 ranks 45th, with 1st being the highest rate.

Deaths peaked at 21 in 2022, as many as 2020, 2021 and 2023 put together, and 2024 had the fewest, 5. Milwaukee County and Manitowoc County, the lakeshore county between Sheboygan and Green Bay, had 14 deaths each, together 28 of the 47. Ozaukee County followed with 5, and Sheboygan and Brown counties had 4 each. FARS files each crash under one route name, so some deaths on the pavement I-43 shares with I-41 and I-94 in Milwaukee may sit under those routes instead, which would make I-43's total a little low.

Counties with the most I-43 crash deaths

Bridges on I-43

The 2025 National Bridge Inventory lists 306 bridges on the I-43 main line. Only 2 rate Poor, under 1 percent. Most of the rest, 251, rate Fair, and 53 rate Good. The median bridge on the route was built in 1976.

In Green Bay, the Leo Frigo Memorial Bridge carries four lanes over the Fox River near its mouth. Wikipedia lists it at 1.51 miles with 120 feet of clearance below; it opened in 1981 and got its current name in 2002. Part of the bridge sagged in late September 2013, and it stayed closed until January 5, 2014. Interstate Guide reports that WisDOT traced the sag to soil conditions that corroded the steel pilings. The bridge was also the site of a fog pileup on the northbound lanes on March 12, 1990 that killed three people.

Tolls on I-43

I-43 has no toll facilities in the FHWA inventory dated January 1, 2023, so the full trip from Beloit to Green Bay is free. Wikipedia's article mentions toll road proposals from years past but no toll lanes on the route today.

How I-43 came together

The Milwaukee-to-Green Bay freeway was built as US 141, starting in the early 1960s; Wikipedia gives 1963 as the start of construction. Interstate Guide notes that early planning maps showed the corridor as an extension of I-57. Wikipedia dates the finished route to 1981, when the last Milwaukee County section, from Port Washington Road to the Marquette Interchange, opened.

The southwestern leg was a state highway first. Wisconsin built the Rock Freeway as WIS 15 between 1969 and 1976, and on November 24, 1987 it became part of I-43 (with signs changed in 1988), which added about 72 miles to the route and retired the WIS 15 number.

Three of its big interchanges have since been rebuilt. Downtown, the Marquette Interchange was reconstructed from October 2004 to September 2008, and its left-hand exits were removed. In Green Bay a directional T replaced the cloverleaf at I-41, and the connection with I-41 and US 141 opened on August 26, 2016. The Beloit end got a directional T of its own at I-39 and I-90, plus a diverging diamond at WIS 81, with work that ran from 2018 to 2021. North of Milwaukee, WisDOT widened 14 miles from the Silver Spring interchange to WIS 60 from four lanes to six and added an interchange at Highland Road; the $550 million project was finished in July 2025. Wikipedia says exit 83 in Mequon became a full interchange in 2023.

I-43 traffic and road conditions

Because I-43 never leaves Wisconsin, one 511 site covers the whole road, from Beloit to Howard. Check it for crash closures, work zones and winter conditions before you head out; the crash figures on this page are five-year totals.

I-43 questions