Champlain is a provincial electoral riding in the Mauricie region of Quebec, Canada, which elects members to the National Assembly of Quebec. It notably includes the eastern portions of the city of Trois-Rivières as well as Saint-Tite, Saint-Maurice and Sainte-Thècle. Its boundaries have remained the same since the 1973 election. However, the boundaries changed for the 2018 election as it gained Hérouxville, Lac-aux-Sables, Notre-Dame-de-Montauban, Saint-Adelphe, Sainte-Thècle, Saint-Séverin and Saint-Tite from Laviolette.