US Highway 25 in the state of Michigan (US 25) was a highway that ran northeasterly from the Ohio state line near Toledo through Monroe and Detroit to Port Huron. Continuing near the foot of the Blue Water Bridge, it proceeded north and northwesterly along the Lake Huron shoreline to the tip of The Thumb in Port Austin. Created with the initial US Highway System in 1926, US 25 followed some roadways dating from the 19th and early 20th centuries, and replaced several state highway designations. The highway was extended to Port Austin in 1933. Starting in the early 1960s, segments of Interstate 75 and Interstate 94 were built, and US 25 was shifted to follow them concurrently south of Detroit to Port Huron. On September 26, 1973, the entire designation was removed from the state. The final routing of the highway is still maintained by the state under eight different designations, some unsigned. (Full article...)
Part of the US Highways in Michigan series, one of Wikipedia's featured topics.