CN York Subdivision

The CN York Subdivision, or York Sub for short, is a railway line in York and Durham regions in the Greater Toronto Area. It runs for 25 miles between the Pickering Junction on the eastern edge of Toronto, and the MacMillan Yard in Vaughan.

Prior to the construction of the York Sub, CN traffic ran through the downtown core along the CN Kingston Subdivision and through the Union Station area. During the 1950s, CN developed a plan to move traffic off of this line to a major new switching yard in what was then farmland far to the north of the city. The switching yard emerged as the MacMillan Yard, and the traffic normally passing through downtown was switched onto two new tracks, the Halton Sub connecting to the west, and the York Sub to the east. Construction of the York Sub took place between 1959 and 1965.

Originally built in what was then farmland, the York Sub is now firmly embedded in the Greater Toronto Area and has little room for expansion. The lines pass from the Kingston Sub to York Sub at Pickering Junction, with a prominent bridge crossing over Highway 401 in an area now surrounded by buildings, including the Pickering Town Centre. The line runs just north of Steeles Ave to Yonge Street, then turns northeast to join John Street from Bayview to Woodbine, Esna Park Road/Alden Road between Woodbine to Warden, and 14th Avenue from Warden to Markham Road. It connects with the Newmarket Sub at Snider, with the Bala Sub at Doncaster, and with the Uxbridge Sub at Hagerman. Originally, there ware diamonds with connecting wye tracks at each of these locations, but since the crossing with the Uxbridge Subdivision was grade separated, the connecting tracks at Hagerman were removed.

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