Saint-Hyacinthe is a city in southwestern Quebec east of Montreal on the Yamaska River. The population as of the 2021 Canadian census was 57,239. The city is located in Les Maskoutains Regional County Municipality of the Montérégie region and is crossed by the Yamaska River, which is perpendicular to Quebec Autoroute 20. Saint-Hyacinthe is the seat of the judicial district of the same name.