Four O'Clock Factoid is a daily feature on Track Twenty-Nine helping to get you through the workday with a bit of useless knowledge.
The Rio Grande Zephyr was a well-known passenger train operated by the Denver and Rio Grande Western before and after the formation of Amtrak. The Zephyr was one of only a few trains not taken over by Amtrak in 1971. It was a descendant of the California Zephyr, which operated from Chicago to Oakland over several railroads. Because the D&RGW elected to opt out of Amtrak, the California Zephyr ceased to exist, with Amtrak operating The City of San Francisco from Chicago to Oakland via Cheyenne and Ogden, while passengers could connect to the Rio Grande Zephyr at Denver and Ogden. In 1983, D&RGW turned the Zephyr over to Amtrak, which renamed the route the California Zephyr, and discontinued use of the route through Ogden.