The pre-2001 city of Longueuil merged with the surrounding municipalities of Boucherville, Brossard, Greenfield Park, LeMoyne, Saint-Bruno-de-Montarville, Saint-Hubert and Saint-Lambert on January 1, 2002.
Jacques Olivier was elected mayor of the merged municipality.
In 2005, Boucherville, Brossard, Saint-Bruno-de-Montarville and Saint-Lambert voted to demerge from Longueuil.
The demerger took effect on January 1, 2006.
Following the demerger referendums, Gladu, leader of the Parti Municipal de Longueuil, won the municipal elections of Longueuil on November 6, 2005.
On April 19, 2009, Claude Gladu announced that he would not seek re-election as mayor of Longueuil.
He and his party instead threw their support behind former Longueuil City Council member Jacques Goyette.