Recently we took our first Amtrak ride in many years. Certain stops along the way said "no checked luggage", whereas some had it - meaning, at certain stops, they don't load and unload baggage into a separate compartment. Some entire trains may not have a baggage car. There were pretty loose guidelines about how much you could carry onboard yourselves, but not totally unrestricted - there were racks above the seats where you could store it during the trip, and some folks had big suitcases up there. Your local station can tell you more.