It's been 25 years for me so things have changed. I also didn't go the whole width of the US. But at the time it was pretty great. One of those life adventures that I've thought about ever since.

I went from Barstow, Ca to Chicago and back at age 18 as a graduation trip with a friend in coach. We spent most of our time (awake and asleep) in the dining and observation cars people watching and talking to folks. There was a whole car of Girl Scouts in uniform for the return trip, which felt a bit like being in Wes Anderson movie... or occasionally The Shining.

We'd jump out at stops just to say we'd been to the city where the stop was. Usually that just meant a quick lap around the train station then back on board, but it was still fun as an 18yo. On the way back we got stuck in the Sierra Nevadas (for only about 6 hours) after the train struck an elk. We were nearish enough to Donner pass that we got to hear some of the older girl scouts (still in uniform) chat about who they'd eat first. I think of that every time I see a cookie stand.