Amtrak does not have USB ports in its current trains, but the new Amtrak trains (Amtrak Airo and the new Acela fleet) will be equipped with USB ports and individual outlets.
Right now, in Coach Class and Business Class, there are two outlets for every seat pair, i.e. one per seat. The outlets are located on the wall near the window, so if you’re sitting in the aisle, you need to ask your seat neighbor for access to the outlet. Acela’s First Class seats have individual outlets. There is at least one outlet in Amtrak’s roomettes and bedrooms.
You can charge your phone on the train, but only if you bring a charger that plugs into a regular outlet.