Montérégie stretches from Montreal's South Shore suburbs into the countryside to the east.
The former have been a battleground between the Liberals and the Bloc Québécois because of the collapse of the Progressive Conservative Party in 1993.
Vaudreuil-Soulanges, west of Montreal, has a significant Anglophone population and can usually be expected to vote Liberal—its 2004 fall to the BQ on election night was one of the biggest surprises on election night.
The fallout from the sponsorship scandal allowed the Bloc to sweep the region in 2006 for the first time, although the Liberals regained the traditional Liberal seat of Brossard-La Prairie in 2008, albeit on a judicial recount.
Renewed Bloc strength allowed them to capture several seats at the NDP and Liberals' expense in 2019.