Rousseau was a merchant, farmer, manufacturer and banker. He served as mayor of Sainte-Anne-de-la-Pérade from 1890 to 1896 and from 1904 to 1905. He was married twice: to Hélène-Catherine Hamelin in 1882 and to Corinne Dufresne in 1886.[1]
Rousseau served in the militia during the Fenian raids and later served as lieutenant-colonel for the 4th Regiment of the Chasseurs Canadiens.