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Why were about 6,500 people relocated during construction of the St. Lawrence Seaway?

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Map showing the St. Lawrence hydrographic system and the five main sectors of the St. Lawrence Seaway project, stretching from Lake Ontario near Kingston through various locks, canals, and dams along the Canada-United States border to Montreal. The map highlights key locations such as the Thousand Islands, International Rapids, Lake St. Francis, Soulanges, and Lachine sections, with detailed labeling of major locks, canals, and power dams. Cross sections of the lock and canal system are depicted — St. Lawrence Seaway The St. Lawrence hydrographic system, with the five main sectors of the St. Lawrence Seaway project.

Approximately 6,500 people were relocated during the construction of the St. Lawrence Seaway primarily because the massive project required significant land and infrastructure changes to accommodate the new waterway and hydroelectric facilities.

The construction of the Moses-Saunders Power Dam and other associated structures in the International Rapids section created the 48-km (30-mile) long Lake St. Lawrence, which necessitated the flooding of riverside communities. To facilitate this development and the creation of the navigation channel, the project also required the raising of bridges and the construction of new dikes, tunnels, and roads.1