LaSalle went from a city to a borough at the time of the merger of the cities on the island of Montréal in 2002. It was in 1912 that Henri Bergevin, Mayor of the municipality of the Parish of Lachine, and the members of his Council, voted in favour of a change of status to become a city. They adopted the name of LaSalle, in honour of the explorer and two-year owner of the fief of Coste Saint-Sulpice. The elected officials' desire, in 1912, was to urbanize the territory and ensure its economic growth.
The municipality of the Parish of Lachine became independent in 1855, within a territory that today includes Dorval, part of Lachine, part of Saint-Pierre as well as LaSalle. From 1669 to 1848, LaSalle therefore formed part of Lachine. During that time, our history and that of our Lachine neighbours was one and the same, before we became LaSalle residents, which explains why, today, the famous Lachine Rapids are located in LaSalle.