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.
Amalgamation of Toronto
In Canada, the creation of municipalities falls under provincial jurisdiction. Thus it was provincial legislation, the "Metropolitan Toronto Act", that created this level of government in 1953. When it took effect in 1954, the portion of York County south of Steeles Avenue, a concession road and common township boundary, was severed from the county and incorporated as the Municipality of Metropolitan Toronto. The area north of Steeles remained in York County, which ultimately became York Region in 1971.