The Exposition Flyer was a passenger train jointly operated by the Chicago, Burlington & Quincy (CB&Q), Denver & Rio Grande Western (D&RGW), and Western Pacific (WP) railroads between Chicago and Oakland, California, for a decade between 1939 and 1949, before being replaced by the famed California Zephyr.

In 1939, the Golden Gate International Exposition opened on Treasure Island in San Francisco Bay. In response, the CB&Q, D&RGW and WP decided to operate a train that could take passengers to the event. Service on the Exposition Flyer began on June 10, 1939.

In the beginning, the train used steam locomotives as motive power and consisted of the heavyweight Pullman standard cars. In later years, however, the train would operate using diesel power and in the final months of service it used streamlined passenger cars 

Initially, the train was supposed to be a temporary route, but, due to the train's popularity, which made it a significant rival to the City of San Francisco, the Flyer remained in operation until 1949.

Courtesy Private Collection.