The first section of I-94 completed with Interstate funds (under the Federal-Aid Highway Act of 1956) was a 12-mile (19 km) section between Jamestown and Valley City, North Dakota in 1958.
North of Chicago, I-94 has been widened from six to eight lanes from Illinois Route 22 (Half Day Road) to just south of the Wisconsin state line at Illinois Route 173 and 95th Street to 159th Street. Starting in 2009, construction began to completely rebuild I-94, including expansion to eight lanes, from the Wisconsin-Illinois border through the Mitchell Interchange in Milwaukee. This construction is expected to be completed in 2021.
In 2005, the I-94 bridge over the Crow River near St. Michael, Minnesota, about 35 miles (56 km) northwest of Minneapolis, was rebuilt. In 2006, a project to widen I-94 east of downtown St. Paul between Minnesota State Highway 120 and McKnight Road from four to six lanes was completed.
The new Marquette Interchange in downtown Milwaukee was completed in August 2008 at a cost of $810 million.
The interchange at 95th Ave. N in Maple Grove, Minnesota was rebuilt with a new, wider bridge that replaced the two-lane bridge there, which was demolished in July 2006.
In Detroit, Interstate 94 was routed over the existing Edsel Ford Freeway, and remained signed as such until the late 1980s when Michigan deemphasized proper names on Interstate guide signs. Its interchange with the Lodge Freeway, built in 1953, is significant as the first full-speed freeway-to-freeway interchange built in the United States.
From September 2007 to October 2008, the Minnesota Department of Transportation (Mn/DOT) added a temporary extra lane to I-94 between northbound I-35W and MN-280 in the Twin Cities to help relieve traffic congestion caused by the collapse of the I-35W Mississippi River bridge. As a result, this portion of I-94 was not up to Interstate Highway standards during this time period.