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.
Borough
It was previously used in Metropolitan Toronto, Ontario, to denote suburban municipalities including Scarborough, York, North York, Etobicoke prior to their conversion into cities. The Borough of East York was the last Toronto municipality to hold this status, relinquishing it upon becoming part of the City of Toronto on January 1, 1998.