Wikipedia: Thornhill is a federal electoral district in Ontario, Canada, that has been represented in the House of Commons of Canada since 1997. It covers its namesake Thornhill neighbourhood, which is split between the Cities of Vaughan and Markham. The Vaughan portion also includes parts of the city east of Highway 400 and south of Rutherford Road, including the largely industrial district of Concord and Vaughan's planned downtown; Vaughan Metropolitan Centre. The part in the City of Markham is restricted its portion of Thornhill itself (but does not include it all) west of Bayview Avenue. The riding was created in 1996 and the east end of the riding was split off into other ridings in 2012. Show more