U.S. Route 90
U.S. Route 90 (US 90) is an east–west United States highway. Despite the "0" in its route number, US 90 never was a full coast-to-coast route; it has always ended at Van Horn, Texas with the exception of a short-lived northward extension to US 62/US 180 near Pine Springs, Texas which lasted less than a year, and the signs on that segment were changed to Texas State Highway 54, traveling from Interstate 10 (I-10) at exit 140A and heading to its northern terminus at US 62/US 180.
Kentucky Route 90
KY 90 was established in 1929 as one of the charter routes of the Kentucky State Highway System. The highway's original western terminus was located in downtown Glasgow at a junction with KY 80 (which at the time was not co-signed with US 68 in this area until the 1940s). Along the route, it connected to certain areas via two ferries, one at Burkesville, and the other at the Whitley/McCreary County line near Cumberland Falls. KY 90's eastern terminus was at a junction with US 25W, but at the time it was in downtown Corbin at the Whitley/Laurel County line. Sometime between 1940 and 1955, US 25W was rerouted to its current route, and KY 90's eastern end was relocated to an area between Corbin and Cumberland Falls. A bridge near the falls was built sometime during that time frame so KY 90 traffic would not be bombarded with rapids that affected ferry service.