York Region (formally knowns as the Regional Municipality of York) is a regional municipality, located between Lake Simcoe and Toronto, in southern Ontario, Canada. It replaced the former York County in 1971. The regional government is headquartered in Newmarket.
The 2011 census population was over 1,000,000. At the previous census in 2006 only 5.7% of the population was rurally based and it had had a growth rate of 22.4% from the previous census of 2001, the third highest amongst all census divisions in Canada.
The earlier York County originally included the City of Toronto and southern townships that joined Toronto to become Metropolitan Toronto in 1954.
Most references to individuals should employ York County rather than York Region unless the event occurred after 1971.