Union Pacific 4-6-6-4 on Archer Hill, Cheyenne, Wyoming, August 1956
This has long been considered as one of the best places to observe Union Pacific action which is constant. No. 3920 was built in 1937, renumbered 3820 in 1944 and scrapped not long after this pic was taken. Today the trains are longer, heavier and have greater power than in steam days although big steam had a more dramatic effect.