The railhead in Benson was founded about a mile from a traditional crossing of the upper San Pedro River (known also as the Middle Crossing), used by the Southern Emigrant Trail and San Antonio-San Diego Mail Line. It was the site of the San Pedro Station of the Butterfield Overland Mail and a wagon depot, the San Pedro River Station, run since 1871 by William Ohnesorgen. In 1878 he had erected a toll bridge over which mining supplies were transported to the new mining camps such as Fairbank and Tombstone. Two years later this bridge marked the location of the railroad bridge that became the terminal site of Benson.