The Challengers were named passenger trains on the Union Pacific Railroad and the Chicago and North Western Railway (which was replaced in 1955 by the Milwaukee Road).

The trains had full Pullman service and coach seating and were an attempt to draw Depression-Era riders back to the rails.

[1] In early June 1935 the Union Pacific transferred the heavyweight coaches and tourist sleeping cars of its Los Angeles Limited to a second section, the Challenger.

The coaches had large reclining chairs and a new color scheme to make the interior more attractive, especially to women passengers.

Station calls were eliminated during sleeping hours, and short-haul passengers were wakened by train crews before their destinations.

On December 8, 1953, the C&NW and UP announced that a Challenger between Chicago and Los Angeles would return with all-streamlined equipment, and on January 10 the first lightweight trainset hit the rails.

The Milwaukee Road embarked upon a repainting program and all its passenger rolling stock received Union Pacific's Armour Yellow and Harbor Mist Gray colors (the MILW retained its traditional orange-and-black livery for freight units).

The Milwaukee Road received that portion of the operating revenue generated between Omaha and Chicago, and furnished 25% of the equipment used on the line.

108 over the CNW (eastbound) consisted of: The meals served in the Challenger's dining cars, while basic (definitely not the first-class fare found aboard the UP's streamliners, where a single meal might cost as much as $1.25) were ample, served on distinctive china and in portions large enough to satisfy even the heartiest traveler's appetite.