Michigan Avenue refers to remnants of Old U.S. Highway 12 that ran from downtown Detroit to Chicago. It was replaced by Interstate 94 in 1952, and the state of Michigan re-routed the US 12 designation to the former route of U.S. Highway 112. In Chicago, stretches of Michigan Avenue form the Magnificent Mile, a wealthy shopping area.

It was an old highway that ran through the middle of many major towns and cities of Michigan between Detroit and Chicago. In most cases the road is still there, and is named either "Michigan Avenue" or "Old U.S. 12". You can still drive the highway from Belle Isle in Detroit all the way to The Magnificent Mile in Chicago. There are only a few places were you have to navigate around the new Interstate. The major break in Old U.S. 12 is in the middle of Michigan half way between the village of Parma and the city of Albion. It's at this point that I-94 cuts south a bit and bisects the old highway, forcing a motorist to navigate north on smaller roads.

The highway is considered an important historic road, similar to Route 66.

See also: Michigan Avenue, a movie by James Benning