SAINT MARYS RIVER

outlet for Lake Superior, forming part of the boundary between Michigan, U.S., and Ontario, Can. Flowing east, then south, for 70 miles (110 km) into Lake Huron, it is an important link in the St. Lawrence Seaway. At Sault Ste. Marie, Ont., the river drops more than 20 feet (6 m) in 1 mile (1.6 km) through the Sault Ste. Marie Rapids. Since navigation there is impossible, the Sault Ste. Marie Canals (or Soo Canals), containing five locks, provide a bypass for the heavy shipping. Large islands divide the river into a series of lakes (Nicolet, George, and Munuscong) and channels (St. Joseph). The river is the narrowest part of the Great Lakes system and a natural crossing site, which was used by the Indians and the early French explorers and missionaries.