 In 1957, one year after construction began on the Glen Canyon Dam, the legislature designated a new State Route 259, heading east and southeast from SR-11 in Kanab to Arizona en route to the dam and adjacent bridge. This replaced about eight miles (13 km) of SR-136 (the original state highway from the 1910s) at its south end, but the remainder was a new roadway, through an area not previously served by improved roads. The route past the dam was initially designated as an alternate route of US-89, but when completed on February 20, 1959 it instead became US-89's mainline, as it was a better route during all weather, and the old route (SR-11 south of Kanab) became U.S. Route 89 Alternate.
