This line was originally constructed as part of the El Paso & South Western, as part of the route between Tucson and Douglas. The EP&SW was leased by the Southern Pacific in the 1920s, and over the years most of its lines that paralleled the SP were abandoned. This segment ran southeast from Mescal, bypassing Benson and passing through Whetstone and Boquillas to Benson Jct., where it joined a line that ran directly from Benson to Douglas. Note: the railroad location "Whetstone" is several miles north of the highway location of the same name. The right of way is relatively intact in several places, except where highways cross over.  North of I-10, the right of way is visible but passes through fenced property.  In the Whetstone area, up until the mid-1990s the grade was easily seen on both sides of Arizona Rte. 90 where it had crossed.  In the late 1990s Arizona route 90 was widened, and several businesses were constructed in the area for tourists visiting Karchner Caverns. The photo above is southeast of the route 90 crossing area, and the right of way can be traveled for a mile or so in this area.