Bridge To Nowhere
This 800-foot-long suspension bridge spanned the Gila River when it was built in 1929, and was named McPhaul Bridge in honor of Henry Harrison McPhaul, "the only Yuma resident who ever became an Arizona Ranger." But it was considered to be too flimsy for modern traffic, and when a dam was built upstream in 1968 the river was diverted and the highway was rerouted over a much smaller bridge. This ultimately proved unwise, as a flood in 1993 destroyed the new bridge while the Bridge to Nowhere, with its broad span and high clearance, probably would have been just fine.
McPhaul Bridge crosses only desert sand and rocks these days, but the Arizona air has kept it remarkably intact. It would have been a fine location for a post-Apocalyptic Charlton Heston film....