Did the old stagecoach route between Benson and Tucson follow what is today’s I-10?
The old Butterfield Overland stage line, which ran across Southern Arizona between 1858-61, ran north of today’s I-10. The route more closely follows the Southern Pacific Railroad tracks, which were laid there in 1881.
In some places, such as the Cienega Springs station at Davidson Canyon, the railroad tracks pass directly over the old stage station. From there, you can travel to Tucson along the north side of the tracks, which are about a mile north of the Interstate highway.
Gerald T. Ahnert’s 1973 book, Retracing the Butterfield Overland Trail Through Arizona, has excellent maps detailing the line.