CN Kingston Subdivision

Canadian National Railway's Kingston Subdivision, or Kingston Sub for short, is a major railway line connecting Toronto with Montreal that carries the majority of CN traffic between these points. The line was originally the main trunk for the Grand Trunk Railway between these cities, although there has been some realignment of the route between these cities. The majority of the Kingston Sub runs close to the northern bank of Lake Ontario and the Saint Lawrence River.

Just east of Newcastle, east of Toronto, the line is joined by the CP Belleville Subdivision, Canadian Pacific Railway's similar mainline route. The two remain nearly side-by-side to the east of Belleville, where the Belleville sub turns north to Smiths Falls. Sections of the Kingston Sub are no longer owned by CN. In particular, CN mainline freight traffic in the Toronto area no longer follows the Kingston Sub, and is re-directed north of the city along the York Sub. The section between Pickering Junction and Union Station in downtown Toronto has been sold to Metrolinx for GO Transit service, part of their Lakeshore East line.