Background
He was born in Shawinigan, Mauricie on June 24, 1932.
He was born in Shawinigan, Mauricie on June 24, 1932.
He worked as a mechanic and in forestry. He ran as for election as Mayor of Trois-Rives, then known as Boucher, in 1978, but lost against Elphège Desrosiers. Mongrain ran again in 1981 and defeated the incumbent.
During Mongrain"s tenure (in 2007), a fire department that services Trois-Rives, as well as Grandes-Piles and Saint-Roch-de-Mékinac was established.