History of Toronto
In 1998, the six municipalities comprising Metropolitan Toronto – East York, Etobicoke, North York, Scarborough, York, and the old City of Toronto – and its regional government were amalgamated into a single City of Toronto (colloquially dubbed the "megacity") by an act of the Government of Ontario. This was despite a municipal referendum in 1997 that was overwhelmingly against amalgamation. Subsequently, Mel Lastman defeated Barbara Hall to become the first elected mayor of the megacity.
Greater Toronto Area
In 1816, Wentworth County and Halton County were created from York County. York County would later serve as the setting for the beginnings of the Upper Canada Rebellion with William Lyon Mackenzie's armed march from Holland Landing towards York Township on Yonge Street, eventually leading up to the battle at Montgomery's Tavern. In 1851, Ontario County (present-day Durham Region) and Peel County were separated from York.