Area codes 450, 579, and 354 are telephone area codes in the North American Numbering Plan in the Canadian province of Quebec, encompassing the off-island suburbs of Montreal, as well as the rest of the Montérégie region southward to the border with New York state. Among the cities in the numbering plan area are Laval, Longueuil, Terrebonne, Saint-Jean-sur-Richelieu, Brossard, Repentigny, Saint-Jérôme, Granby, Blainville and Saint-Hyacinthe.

Saint-Jean-sur-Richelieu is a city in eastern Montérégie in the Canadian province of Quebec, about 40 kilometres (25 mi) southeast of Montreal, located roughly halfway between Montreal and the Canada–United States border with the state of Vermont. It is situated on both the west and east banks of the Richelieu River at the northernmost navigable point of Lake Champlain. As of December 2019, the population of Saint-Jean-sur-Richelieu was 98,036.