As others have said, this is Hidden City ticketing. But one thing to check is pricing two one-ways. E.g. wherever you are willing to drive to from Halifax (X) to NYC. Then pricing a separate one-way return to YHZ. Most (but not all) domestic US flights price as two one-ways, but this isn't true on Intl flights.

If you want to play with Hidden city ticketing, find flights that connect through NYC and price the one-ways. You will be able to see if that will work for you. Sometimes it is necessary to book on multiple carriers. ITA is a good resource.