The train is about to leave Penn Station in New York City. A twenty-something woman hoists her roller bag into the overhead compartment and settles into the window seat. An announcement crackles through the overhead speakers, the train will be near capacity. An elderly couple shuffles by, dragging their luggage, hoping to find two seats together. A man, perhaps a college student, stops. “Is this seat taken?” “No.” The woman smiles and pulls her coat into her lap. He sits, put