464 feet in length and standing over 75 feet above the riverbed. It was the biggest trestle to be built along the Atlantic and Lake Superior line, and together with the dam that adjoined it represented a colossal technological undertaking for the Atlantic Mine.
Built on the concrete footing used for this unusual steel dam, it escaped the scrap metal drive of WW2.
It was used while the nearby copper mines hauled out millions of tons of copper, and then, like all boom town businesses, was abandoned when the big resource was exhausted.
Photos all from http://www.coppercountryexplorer.com/2013/11/hidden-in-plain-site/
3 steel dams were built, 1 still exists and is functional
Only three steel dams were constructed in the U.S., and today the Ashfork-Bainbridge Dam is the only one that still holds a reservoir. https://www.atlasobscura.com/places/ashfork-bainbridge-steel-dam