(Restructured as regional municipality)
|Incorporated||1792 (created from Home District)|
|Dissolved||1971 (reorganized into the Regional Municipality of York)|
|o Total||2,392.17 km2 (923.62 sq mi)|
|The following figure was the size of the county from 1851 to 1953|
|Time zone||UTC-05:00 (Eastern)|
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.
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.
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 Regional Municipality of York.
The following table is a list of historic municipalities that were at one point situated within York County.
|Type of municipality[note 1]||Name of municipality||Year severed from York County||Present municipality||Present upper-tier government|
|Township||Albion||1851||Town of Caledon||Peel Region|
|Town||Aurora||1971[note 2]||Town of Aurora||York Region|
|Township||Caledon||1851||Town of Caledon||Peel Region|
|Township||Chinguacousy||1851||City of Brampton
Town of Caledon
|Township||East Gwillimbury||1971[note 2]||Town of East Gwillimbury||York Region|
|Township||East York||1954||City of Toronto[note 3]|
|Township||Etobicoke||1954||City of Toronto[note 3]|
|Village||Forest Hill||1954||City of Toronto[note 3]|
|Township||Georgina||1971[note 2]||Town of Georgina||York Region|
|Township||King||1971[note 2]||Township of King||York Region|
|Town||Leaside||1954||City of Toronto[note 3]|
|Village||Long Branch||1954||City of Toronto[note 3]|
|Village||Markham||1971[note 2]||City of Markham||York Region|
|Town||Mimico||1954||City of Toronto[note 3]|
|Town||New Toronto||1954||City of Toronto[note 3]|
|Township||Nelson||1816||City of Burlington||Halton Region|
|Town||Newmarket||1971[note 2]||Town of Newmarket||York Region|
|Township||North Gwillimbury||1971[note 2]||Town of Georgina||York Region|
|Township||North York||1954||City of Toronto[note 3]|
|Village||Oshawa||1851||City of Oshawa||Durham Region|
|Township||Pickering||1851||City of Pickering||Durham Region|
|City||Richmond Hill||1971[note 2]||City of Richmond Hill||York Region|
|Township||Scarborough||1954||City of Toronto[note 3]|
|Village||Stouffville||1971[note 2]||Town of Whitchurch-Stouffville||York Region|
|Village||Swansea||1954||City of Toronto[note 3]|
|Township||Thorah||1851||Township of Brock||Durham Region|
|City||Toronto||1954||City of Toronto[note 3]|
|Township||Toronto||1851||City of Mississauga
City of Brampton
|Township||Toronto Gore||1851||City of Brampton
City of Mississauga
|Township||Trafalgar||1816||Town of Oakville||Halton Region|
|Township||Uxbridge||1851||Township of Uxbridge||Durham Region|
|Township||Vaughan||1971[note 2]||City of Vaughan||York Region|
|Town||Weston||1954||City of Toronto[note 3]|
|Township||Whitby||1851||Town of Whitby||Durham Region|
|Township||Whitchurch||1971[note 2]||Town of Whitchurch-Stouffville||York Region|
|Township||York||1954||City of Toronto[note 3]|
The seat of government for York County was situated in Toronto (named York prior to 1834) from 1792 to 1953. After the creation of Metropolitan Toronto in 1953, the seat of government for York County was moved to Newmarket.
Offices used by York County included: