Not much is known about this short spur. In all likelyhood it started out as the original routing of the Southern Pacific (via susbidiary Arizona Eastern) mainline east of Phoenix until the line was relocated to its current routing through Magma. From then on, it was most likely used as a short cut-off by the Copper Basin Railway in reaching the new Southern Pacific routing at Poston Station. While it shows up on maps as early as 1895, it is absent on a 1948 railroad map.
Today, little evidence remains of the line. All lineside structures, bridges, culverts have been removed. The only clues that remain are the rocks in areas that were once used as ballast.
See also Dock to Poston Station.
Thanks to Mike Palmer for contributing information about this route.