The City of Denver was a streamlined passenger train operated by the Union Pacific Railroad between Chicago, Illinois, and Denver, Colorado. It operated between 1936 and 1971. From 1936–1955 the Chicago and North Western Railway handled the train east of Omaha, Nebraska; the Chicago, Milwaukee, St. Paul and Pacific Railroad (the "Milwaukee Road") handled it thereafter. The train was the fastest long-distance train in the United States when it debuted in 1936, covering in 16 hours. For almost its entire career its principal competitor was the Chicago, Burlington and Quincy Railroad's Denver Zephyr. When Amtrak assumed operation of most intercity trains in the United States in 1971, it discontinued the City of Denver, preferring to use the Burlington's route between Chicago and Denver. On its launch in 1936 the City of Denver used a pair of articulated trainsets built by Pullman-Standard. The streamliners would remain in service until 1953, when conventional locomotive-hauled rolling stock replaced them. The City of Denver always carried both sleeping cars and coaches. A notable feature of the 1936 version of the train was the "Frontier Shack" tavern, which had the feel of a Western saloon. History The articulated streamliners of the 1930s consisted of power cars and passenger cars semi-permanently coupled together, with the cars sharing trucks. By the end of 1935 the Union Pacific Railroad already operated four such equipment sets, each on a different route: the M-10000 (City of Salina), M-10001 (City of Portland), M-10002 (City of Los Angeles), and M-10004 (City of San Francisco). While the M-10000 made the round-trip between Kansas City, Missouri and Salina, Kansas in a single day, the other three sets required multiple days to run from Chicago to their respective namesakes. The infrequent departure schedule led Union Pacific to advertise a train's "sailings", as though it were an ocean liner. In December the Union Pacific and Chicago and North Western Railway (C&NW) announced a new Chicago–Denver "high-speed" service, to be served by a pair of trainsets enabling daily service, the M-10005 and M-10006. The projected running time of 16 hours was a full nine hours faster than the best schedule at that time. The new trains had a maximum speed in excess of and averaged over the trip. This made it the fastest scheduled long-distance train in the United States. The Union Pacific emphasized that the improved schedule would "save a business day." At the same time