The Metro Junior Hockey League was an influential top level Canadian Junior "B" league that spawned much change in the Ontario Hockey Association. It was formed in 1950 under the name "Big Six", and in 1954-55 it was known as the "Big Nine" league. In 1955 it became known as the Metropolitan Junior B league, often with the Toronto predicate as the teams were in the Toronto metropolitan area. In 1991 it became a Junior "A" league and merged with the Ontario Provincial Junior A Hockey League in 1998.