Track work, waiting on local traffic (especially commuter), train police pulling someone off the train, etc.

You can tell the people who've never taken the train before when they start asking why it's stopped.

I say this out of love, to set expectations. Cross country, if you want to get somewhere ASAFP take a plane. If you want to enjoy a leisurely week+, drive. If you're willing to spend a few days for the scenery of a road trip without having to do the logistics, take the train.