Sault Sainte Marie Canals, two ship canals bypassing the rapids on the St. Marys River between Lake Superior and Lake Huron, at the cities of Sault Ste Marie, Mich. and Ont. The Canadian canal (1.4 mi/2.3 km long and 60 ft/18 m wide), which has one lock, was opened in 1895. It follows the route of the first canal constructed around the rapids (1797–98) by a fur company. The U.S. canal (1.6 mi/2.6 km long and 80 ft/24 m wide) was constructed (1853–55) by the state of Michigan and has since been reconstructed by the federal government to accommodate larger vessels; it has four locks. Although closed by ice during the winter, the toll-free canals are among the country's busiest and are a vital link in the Great Lakes Waterway. Most of the ships pass through the larger and deeper U.S. canal. The waterways are popularly called the Soo Canals.
See J. N. Dickinson, To Build a Canal (1981).