The Montreal Subdivision is a railroad line owned by the St. Lawrence and Adirondack Railway and CSX Transportation in the U.S. state of New York and Canadian province of Quebec. Operations are by CSX Transportation. The line originally ran from Massena, New York northeast to Kahnawake, Quebec along a former New York Central Railroad line. At its south end, the St. Lawrence Subdivision continues south; its north end was at Adirondack Junction, a junction with the Canadian Pacific Railway's Adirondack Subdivision, along which it had trackage rights north over the Saint-Laurent Railway Bridge into Montreal.