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How did early St. Lawrence canals help boats navigate the river in the 1780s?

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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.

In the early 1780s, shallow canals were dug along the St. Lawrence River to facilitate navigation for specific types of vessels. These canals were designed to accommodate bateaux and Durham boats—long, tapering vessels characterized by their flat bottoms and auxiliary sails—allowing them to bypass natural obstacles that had previously hindered travel into the interior of North America.1