The Second World War results in the arrival of a large number of workers who come to work at the Arvida smelter. The parish of Saint-Jacques-le-Majeur develops in this context in order to accommodate the large population growth of the 1940s. The church creates the parish in 1943, but the church is only built after the war, in 1947.
Designed to accommodate 850 new parishioners, Saint-Jacques Church is the work of two architects : Léonce Desgagné and Paul Boileau. The building is characteristic of the architects’ late 1940s designs. Along with the Manoir du Saguenay, Saint-Jacques Church is one of the best examples of regionalist architecture. Indeed, the architecture of its ensemble (church and presbytery) evokes the traditional churches of Quebec by its rectangular nave, its roof with curved eaves and its siding formed of large slabs of limestone. Saint-Jacques Church closes in 2004. The building is acquired by Québec Issime in 2012.