York County is a historic county in Upper Canada, Canada West, and the Canadian province of Ontario. York County was created on 16 June 1792 and was part of the jurisdiction of the Home District of Upper Canada. It originally comprised all of what is now the regional municipalities of York, Peel, and Halton, and the city of Toronto, as well as parts of Durham Regional Municipality and the city of Hamilton. Toronto was the county seat. In 1816, Wentworth and Halton counties were created from York County. In 1851, Ontario and Peel counties were separated from York.