This abandoned line was 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. While it shows up on maps as early as 1895, it is absent on a 1948 railroad map.
A temporary 3-foot narrow-gauge wooden trestle was built near Olsberg in order to facilitate building of the Gila River Irrigation Project. The bridge was washed out by flooding just 4 weeks later, but fortunately after the bridge had served its purpose.
The western end of the abandoned section is "in the middle of nowhere" near Sacaton. There is an active shipper a couple miles west of the end-of-track who receives shipments in covered hoppers, as can be seen today; this marks the end of the active Chandler Branch of the Union Pacific. The eastern end of the abandoned section still has a stub track remnant about 1/2-mile long that is used to store maintenance-of-way cars. There are also huge piles of used railroad ties in the area.
See also The Florence Branch.
Thanks to Mike Palmer for contributing information about this route.