AmTrak Zephyr also known as California Zephyr, travels roughly 2,500 miles between Chicago and San Francisco. Many people I have spoken to, that had the chance to ride the Amtrak Zephyr, agreed that it could be one of the most scenic train travels that they ever took within the United States.
While the trip sounds very exciting, and definitely something to look forward to, having access to WiFI could be as important as the itinerary itself, depending how bad you need internet connection throughout those 52 hours of travel.

Does AmTrak Zephyr have WiFi?

Unfortunately as of today, AmTrak Zephyr doesn’t offer WiFi on-board.
How can I connect to the internet while traveling on Amtrak Zephyr?
One way to connect to the internet would be via your phone, using it as a WiFi hotspot. However doing so,

depending on your mobile carrier

, you might have to get extra charges, so make sure you check that out with your carrier.
It is well worth to mention that there are some sectors where coverage is bad, or nonexistent, again, depending on your carrier.
Based on my experience which was years ago, coverage was bad to nonexistent at the border of Iowa to Nebraska (Omaha) and between Granby and Glenwood Springs.
Train stations along the way might have some free fast WiFI, however stops are usually between 10-30 minutes long, which probably won’t be nearly enough for this reason.