| Union Pacific 4004 leads a westbound extra along the alternate mainline between Perkins and Harriman. The alternate mainline, also known as main three, was built in the early 50s, and allowed trains to climb Sherman Hill without helpers. The route was farther south than the original mainline, passing through Harriman and Perkins before turning north to Laramie. Obtained from Union Pacific Steam: Big Boy Portraits (Bush, Ehernberger) |