York South was an electoral district (or "riding") in Ontario, Canada, that was represented in the House of Commons of Canada from 1904 to 1979. The riding is notable for the 1942 federal by-election in which newly elected Conservative leader Arthur Meighen was defeated in his attempt to win a seat in the House of Commons by the Co-operative Commonwealth Federation's (CCF) candidate (assisted by the Liberals). The election was a major breakthrough for the CCF, and ended Meighen's attempt to return to politics. In later years, it became known as perennial leaders' riding, the home district for both CCF and New Democratic Party (NDP) leaders Ted Jolliffe, Donald C. MacDonald, David Lewis and Bob Rae. History York South was created in 1903 as "the south riding of York" from parts of York East and York West ridings. It initially consisted of the township of York, and the towns of East Toronto, North Toronto, and Toronto Junction. As is suggested by the names of the towns in the riding, the constituency abutted on the city of Toronto's northern border. In 1914, it was called "South York", and redefined to consist of the villages of Richmond Hill and Markham, the township of Markham, the town of Leaside, and the township of York (excluding parts included in the riding of West York); and those portions of the city of Toronto not included in the ridings of West York, Parkdale, North Toronto, East Toronto, Centre Toronto, West Toronto, South Toronto and East York. In 1924, it was called "York South", and consisted of all that part of the county of York lying east of Yonge Street, south of the township of Markham and outside the city of Toronto. In 1933, York South was defined to consist of all that portion of the township of York not included in the electoral district of West York, the town of Weston and the village of Forest Hill. From 1947, it consisted of the village of Forest Hill and a portion of the township of York. In 1952, it consisted the village of Forest Hill and a re-defined portion of the township of York. As time progressed and the population grew, the riding shrank in size so that it consisted of what was later called the Borough of York in the middle western part of Metropolitan Toronto and some surrounding areas. While it was originally a largely