... old Transcontinental Railway route ...
Been there. The Spiral Jetty is out that way. You should also check out the old navigation arrows for CAM route #5 (SLC to Pasco, WA) while you are out there.
There were five Contract Air Mail (CAM)
routes in and out of SLC in the late 20's and early 30's. CAM-5 was awarded to Varney Air Lines. Varney was founded in 1926 by Walter T.
Varney. CAM-5 air service was inaugurated with both north and south flights on
April 6, 1926 between Elko Nevada and Pasco Washington with an interim stop in
Boise Idaho. In order to provide a safer route during the winter, Salt Lake City was substituted for Elko beginning on October 1, 1926. Postal mail covers carried on the
inaugural flight between each point of landing and take-off are collectible and are
known as CAM-5 covers.
Varney Air Lines used New Swallow bi-planes with Curtiss engines for this initial
April 6, 1926 air service. The New Swallow bi-planes were built by the Swallow
Company which survived the dissolution of the E M Laird Aviation Company
(partnership of Laird, Burke and Moellendick).