The Western Pacific Railroad was built in the last decade of the nineteenth century and the first decade of the twentieth century, to form the Pacific outlet for Jay Gould's Missouri Pacific and Denver & Rio Grande Western railroads. In later years, after Gould interests had lost control, and after D&RGW had secured direct western access to Denver, WP formed an alliance with D&RGW and Chicago, Burlington & Quincy to run trains between Oakland and Chicago. In 1949, this led to the introduction of the famous California Zephyr streamliner, with its multiple dome cars. In 1957, part of the line in the lower Feather River region was relocated by the builders of the giant Oroville Dam, to get it out of the area to be flooded when the dam was completed. CZ was taken off in 1968. (Amtrak later revived the name, but Amtrak's train uses the ex-SP Donner Pass route, not the Feather River route). In 1982, WP disappeared into the maw of Union Pacific, in a merger that also saw Missouri Pacific incorporated into UP.
The “high-line” to the GN connection at Bieber was constructed in the early 1930s.