Actually, since there is confusion, going back to the very beginning -- For the train route I myself am familiar with, the line between New York and Poughkeeps

Actually, since there is confusion, going back to the very beginning -- For the train route I myself am familiar with, the line between New York and Poughkeepsie, two different train systems serve the route, Amtrak (the company that does the nation-wide train service in the United States) and Metro North, a commuter-rail line associated with New York's MTA, via their Hudson Line. I started with the Amtrak costs because the New York <-> DC train is an Amtrak train; most daily commuters will be using the Metro North, as it is cheaper.