Blainville—Deux-Montagnes initially consisted of the cities of Deux-Montagnes and Sainte-Thérèse; the towns of Blainville, Boisbriand, Lorraine, Rosemère, Saint Eustache and Sainte-Marthe-surle-Lac; and the village municipality of Pointe-Calumet and the parish municipality of Saint-Joseph-du-Lac in the county of Deux-Montagnes. In 1987, it was redefined to consist of the towns of Blainville, Boisbriand, Deux-Montagnes, Lorraine, Rosemère, Saint-Eustache, Sainte-Marthe-sur-le-Lac and Sainte-Thérèse.