At Weso, Nevada, the Southern Pacific and Western Pacific began a paired traffic agreement which dated back to World War I. The two roads had parallel single track lines across the northern half of the state, and in the press of wartime traffic agreed to have eastbound trains use the Western Pacific main and westbounds use the Southern Pacific. This arrangement was in place all the way to Alazon in eastern Nevada, and remained in force until rendered moot by the Union Pacific's acquisition of both roads, in 1983 and 1997 respectively. Here we're looking down the Southern Pacific main, with the Western Pacific at left. The connecting track between the two is just visible before the second signal in the distance.
