At the New York border, PA 5 becomes New York State Route 5 (NY 5), and the Seaway Trail continues along it to the Erie County border. Route 5 and the Seaway Trail cross Cattaraugus Creek together at the county line, but the trail quickly turns off to the west and then back north again along Old Lake Shore Road, to more closely follow the shore of Lake Erie. The Seaway Trail rejoins Route 5 in Hamburg, and they continue north into the city of Buffalo, the largest city on the Seaway Trail.