Interstate 90 in Wisconsin

Interstate 90 (I-90) runs east–west through the western, central and southern portions of the U.S. state of Wisconsin. About 187 mi of I-90 lie in the state.

All 187 miles of I-90 in Wisconsin have a speed limit of 70 mph.

Route description
The highway enters from Minnesota over the Mississippi River just northwest of La Crosse. The freeway passes north of La Crosse and south of Onalaska as it heads towards Tomah. Once there, it joins I-94. The two Interstates run concurrently for the next 91.76 mi to Madison. The highway collects Interstate 39, 63 mi southeast of Tomah (near Portage). This concurrency of about 30 mi is one of only two three-route concurrency of the Interstate Highway System existence, the other being in Milwaukee. I-39 continues along I-90 for the remaining 78 mi in Wisconsin.

I-94 breaks away eastward toward Milwaukee at what is commonly known as the Badger Interchange, where the three Interstates meet with WIS 30. The remaining routes continue south to Janesville and Beloit before exiting the state.

History
In 1959, I-90 was extended north from Rockton Road, the Northwest Tollway's (now Jane Addams Memorial Tollway's) northern terminus, in Illinois to US 14 near Janesville, Wisconsin. In 1961, another section of I-90 was opened. This section ran from US 12/US 18 (later moved slightly southward) near Madison to US 12/US 16 (now US 12/WIS 16) near Wisconsin Dells. In 1962, a connection between both opened sections opened to traffic. In 1964, I-90 was extended northwestward to US 12/US 16 (now US 12/WIS 16) near Tomah.

The Dresbach Bridge, spanning the Mississippi River west of La Crosse, was dedicated and opened to traffic on October 12, 1967. By 1969, another separate section of I-90 was opened, traveling from the Minnesota state line to US 16 (now WIS 16) near La Crosse. Later, both opened sections were then connected together.

The Dresbach Bridge was replaced by the states of Minnesota and Wisconsin in 2016 under the former's program to replace outdated bridge designs following the 2007 I-35W bridge collapse. The old bridge was closed in April 2016 and the new structure opened in October.

Starting in 2015, the 45 mi, southernmost section of I-39/I-90 (from US 12/US 18 to the Illinois state line) underwent a major reconstruction project. This involved widening the corridor to six lanes (eight lanes in the Janesville area) and reconfiguring all interchanges, including the I-43/WIS 81 interchange. The overall project was completed in 2021.