Well, almost. When the Western Pacific received permission to discontinue its portion of the original CZ, the Chicago – Oakland route was changed from one through train to three connecting services. The Burlington maintained its original route, renaming the Chicago – Denver train California Service, and reducing the frequency from daily to triweekly. The Rio Grande also reduced train frequency to triweekly on its newly instituted Rio Grande Zephyr, and extended its route beyond Salt Lake City to facilitate connections to the UP/SP City of San Francisco.
When the Rio Grande opted to stay out of Amtrak, the replacement Chicago – San Francisco service was covered by the Chicago – Denver Denver Zephyr on the Burlington, with the San Francisco Chief operating between Denver and Oakland via the UP Overland Route. The Rio Grande Zephyr, meanwhile, covered the parallel route between Denver and Ogden through Colorado. After about a year, Amtrak combined its two trains into a single San Francisco Zephyr. This arrangement stuck until the Rio Grande finally decided to join Amtrak in 1983.
With a discontinuance date of April 24, 1983 for the RGZ, Amtrak planned to reroute the San Francisco Chief between Ogden and Denver over the Rio Grande, and rename it the California Zephyr, but nature had other ideas. A few weeks before the change, a huge mudslide in Thistle, Utah severed the Rio Grande main line, and the post-RGZ Amtrak service remained on the UP until July 20. So the train seen here in Denver, scheduled to be the first eastbound California Zephyr, is just another San Francisco Chief.