Ontario was a federal electoral district represented in the House of Commons of Canada from 1925 to 1997. It was located in the province of Ontario. This riding was created in 1924 from Ontario South riding. It initially consisted of the townships of Pickering, Whitby (East and West), Reach, and Scugog, and the city of Oshawa in the county of Ontario. In 1947, the townships Scott and Uxbridge were added to the riding. The electoral district was abolished in 1996 when it was redistributed between Pickering—Ajax—Uxbridge and Whitby—Ajax ridings.