The Barber Lumber Company wanted a rail line along the river that could haul timber out of the mountains. They owned the right of way where the line would need to go. The Bureau of Reclamation needed a way to get material back and forth to and from the dam site, so they worked out an agreement with Barber Lumber company where Reclamation would lease the tracks and run the railroad. That made the Arrowrock and Barber Railroad the first publicly owned line in the nation.
The Arrowrock and Barber Railroad ran from—wait for it—Arrowrock to Barber and back. The Oregon Shortline ran from Barber to the new Reclamation office in Boise, where materials were warehoused and sent to the construction site as needed. The Reclamation Service Boise Project Office, at 214 Broadway Avenue in Boise, was listed on the National Register of Historic Place in 2010.