In the Montreal metropolitan area, the South Shore refers to all the cities located south and east of the Island of Montreal, on the south shore of the St. Lawrence River. It includes the agglomeration of Longueuil (population 434,711) and the regional county municipalities (RCMs) of Roussillon (population 185,568), La Vallée-du-Richelieu (population 131,803), and Marguerite-D'Youville (population 80,313).
French colonization of the territory between the St. Lawrence and the Richelieu Rivers began in the 18th century with the establishment of the seigneury of Sault-Saint-Louis in 1660, the seigneury of Îles-Percées (Boucherville), and the barony of Longueuil in 1668.