York County is a historic county in Upper Canada, Canada West, and the Canadian province of Ontario. It was organized by the Upper Canada administration from the lands of the Toronto Purchase and others. Created in 1792, at its largest size, it encompassed the area that presently comprises the City of Toronto, the regional municipalities of Halton, Peel, and York as well as portions of Regional Municipality of Durham and the City of Hamilton. However by 1851, York County only consisted of the areas presently comprising Toronto and Regional Municipality of York. In 1953, York County was split again, with the area south of Steeles Avenue forming the Municipality of Metropolitan Toronto. York County was formally dissolved in 1971, with its remaining municipalities reorganized as the Regional Municipality of York. History 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 City of Toronto, the regional municipalities of Halton, Peel, and York as well as portions of the Regional Municipality of Durham, and the City of Hamilton. The town of York, later incorporated as the City of Toronto in 1834, served as the initial seat for the county. Once Toronto was incorporated, it was severed from York County, although county offices remained located in Toronto. In 1816, Wentworth and Halton counties were created, with portions of York County transferred to the new counties. In 1851, the western portions of York County were separated to form Peel County. In the same year, the eastern riding of York County was separated from York to form Ontario County. In April 1953, the Metropolitan Toronto Act was passed in the Legislative Assembly of Ontario. This saw municipalities south of Steeles Avenue severed from York County and forming the Municipality of Metropolitan Toronto. As a result of this separation, the county offices for York County were moved from Toronto to Newmarket. The Act went into effect on 1 January 1954. At a meeting in Richmond Hill on 6 May 1970, officials representing the municipalities of York County approved plans for the creation of a regional government entity to replace York County. In 1971, the remaining portion of York County was dissolved by restructuring it into the new Regional Municipality of York. Historic municipalities The following table is a list of historic municipalities that were at