US highway 25 is a road with a long history. It was one of the original inter-state federal highways laid out in the United States Joint Board on Interstate Highways plan of 1925, and was officially commissioned when the plan was submitted to the states in November, 1926.
Though it was conceived as a regional highway, in one part of the country US 25 assumed major inter-city route status: for many years, it was the mainline route between Detroit, Michigan and Knoxville, Tennessee. As originally commissioned, US 25’s northern terminus was located in Port Austin, Michigan. From there the route ran through Detroit; Toledo, Dayton, and Cincinnati, Ohio; Lexington, Richmond, and London, Kentucky; Knoxville; Asheville, North Carolina; Greenville, South Carolina; and finally reached its southern terminus at Augusta, Georgia, for a total length of over 1100 miles.
In southern Kentucky (near Corbin, home of the first Kentucky Fried Chicken restaurant) the route splits into two branches, US 25W and US 25E. The split continues to just outside Newport, Tennessee, where the two routes recombine into regular US 25.
For most of its routing through Ohio and Michigan, US 25 followed the path of another historic road, a branch of the old Dixie Highway. As the Dixie Highway, US 25 crosses two other famous routes: the Lincoln Highway (US Highway 30) at Beaverdam, Ohio; and the National Road (US Highway 40) just north of Dayton, Ohio.
As with many other original federal highways, the newer Interstate highways replaced parts of US 25. In the late 1960s, it was replaced by Interstate 94 between Port Huron and Detroit; and by Interstate 75 between Detroit and Cincinnati, Ohio. At first US 25 was rerouted onto the Interstate highways; then, in 1973, the highway departments of Ohio and Michigan petitioned the American Association of State Highway Officials to remove the 25 designation altogether. Though US 25 was technically truncated back to Kentucky, its northern terminus is actually in Ohio, at the northern end of the Clay Wade Bailey Bridge in Cincinnati. The remainder of the route, from Kentucky down through Georgia, is mostly unchanged.
Bessert, Christopher J. "Michigan Highways", Historic US 25. 1997-2003. <http://www.michiganhighways.org/listings/HistoricUS-025pg2.html>. (31 January - 2 February 2004) .
Sanderson, Dale. "Highway Ends", End of US Highway 25. 2000-2003. <http://www.geocities.com/Yosemite%2FFalls%2F3369/HwyEnds/End025/end025.htm>. (31 January - 2 February 2004) .