This is mostly true, but in fact the route currently used by the California Zephyr through the Rockies (Salt Lake City - Soldier Summit - Moffat Tunnel - Denver) was built by the Denver and Rio Grande Western Railroad or its predecessors [1]; the section in question was completed no earlier than 1883.
The more famous railroad finished in 1869 takes a more northerly route, through Ogden instead of Provo, and through Rawlins, Laramie, and Cheyenne in Wyoming instead of adjacent to I-70 through Grand Junction and Denver.
The mountainous sections of the Zephyr, specifically the crossings of the Rockies and the Sierras, are indeed the least competitive vs. driving. Based off of the official timetable [2], the Zephyr takes:
~9 hours between Chicago and Omaha vs. 7.5 hours driving
~8.5 hours between Omaha and Denver vs. 7.5 hours driving
~15 hours between Denver and Salt Lake City vs. 8 hours driving
9 hours between Salt Lake City and Reno vs. 7.5 hours driving
7.5 hours between Reno and Emeryville vs. hours 3.5 driving
Lengthening the driving time to include breaks, the train is viable between Chicago and Denver, and between Salt Lake and Reno, but is nearly twice as slow as driving on other parts of the route.
Stating the obvious here, I know, but Chicago-Denver has so many flights it's not even funny, United, American, Spirit, Southwest, Frontier, well over twenty flights any day.
The more famous railroad finished in 1869 takes a more northerly route, through Ogden instead of Provo, and through Rawlins, Laramie, and Cheyenne in Wyoming instead of adjacent to I-70 through Grand Junction and Denver.
The mountainous sections of the Zephyr, specifically the crossings of the Rockies and the Sierras, are indeed the least competitive vs. driving. Based off of the official timetable [2], the Zephyr takes:
~9 hours between Chicago and Omaha vs. 7.5 hours driving
~8.5 hours between Omaha and Denver vs. 7.5 hours driving
~15 hours between Denver and Salt Lake City vs. 8 hours driving
9 hours between Salt Lake City and Reno vs. 7.5 hours driving
7.5 hours between Reno and Emeryville vs. hours 3.5 driving
Lengthening the driving time to include breaks, the train is viable between Chicago and Denver, and between Salt Lake and Reno, but is nearly twice as slow as driving on other parts of the route.
[1] https://en.wikipedia.org/wiki/Denver_and_Rio_Grande_Western_... [2] https://www.amtrak.com/content/dam/projects/dotcom/english/p...