Sainte-Martine, Quebec  Sainte-Martine is a municipality in Beauharnois-Salaberry Regional County Municipality in the Montérégie region of Quebec, Canada. The population as of the Canada 2016 Census was 5,461. The municipality is made up of a large northern section and a small unattached southern area that was known as the municipality of Saint-Paul-de-Châteauguay until its merger with Sainte-Martine on September 9, 1999. The following locations reside within the municipality's boundaries:  The Exo du Haut-Saint-Laurent sector provides commuter and local bus services.