U.S. Route 12 - History

History

Since the highway's creation in 1926, the eastern terminus has always remained within a few blocks of this point.

• 1926: Cadillac Square at the convergence with US-10, US-16, US-25 and US-112. U.S. 12 goes along Grand River. The original ending was at Miles City, Montana.
• 1939: AASHTO approved a request to extend U.S. 12 to Yellowstone National Park.
• 1956: U.S. 12 was rerouted along the Lodge Freeway, ending on Jefferson; the terminus moved four blocks southeast, to the corner of Woodward Avenue (US-10) and Jefferson Avenue.
• 1959: Extended to Missoula, Montana.
• 1962: After I-94 is completed across Michigan, it is no longer co-signed with US-12. The US-12 route designation is moved to the former route of US-112, which is decommissioned. US-12 now runs along Michigan Avenue and again ends at Cadillac Square. It was extended to Lewiston, Idaho.
• 1967: Extended to Aberdeen, Washington, to its present terminus at U.S. Route 101.
• 1970: US-10 is rerouted from Woodward to the Lodge Freeway and Jefferson. At this time U.S. 12 apparently is extended along Woodward, to again terminate with US-10 at Woodward and Jefferson, though with the designations flip-flopped from their 1956 routing.
• 2001: The City of Detroit and the Michigan Department of Transportation, in a series of jurisdictional transfers, move the terminus back four blocks, to again be at Cadillac Square.
• 2005: In another transfer, the U.S. 12 terminus is truncated another four blocks, to end at the Patrick V. McNamara Federal Building, on the corner of Michigan and Cass Avenues.

The western terminus was gradually extended westward, until it met up with the Pacific Ocean.