Long Sault

This article refers to the rapid on the St. Lawrence River, for the once named Long Sault Rapids on the Ottawa River which was involved in the Battle of Long Sault and the Beaver War, please see Carillon, Quebec or Carillon Canal

Long Sault was a rapid in the St. Lawrence River west of Cornwall.

The Long Sault created a navigation barrier along the river for much of its history, necessitating the construction of the Moses-Saunders Power Dam, part of the St. Lawrence Seaway, in the 1950s as the size of ships and the volume of shipping traffic along the river began to exceed the capacity of the area's canal locks.

The construction, in part, required the flooding of a large swath of land near the rapids, both to facilitate a hydroelectric dam and to make the rapids area more navigable. The flooded region includes Ontario's Lost Villages.

The town of Long Sault, Ontario and the Long Sault Parkway both take their name from the rapids.