Last Steam Locomotive Runs from North Platte to Cheyenne
Union Pacific at one time owned 105 Challenger locomotives. Built between 1936 and 1943, the Challengers were nearly 122 feet long and weighed more than one million pounds. Articulated like their big brother, the Big Boy, the Challengers had a 4-6-6-4 wheel arrangement. They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to passenger trains operating through mountain territory to California and Oregon. As the efficiency of diesels overtook steam, UP relegated its Challengers to the Wyoming lines beginning in the mid-1950s.