The steamship Illinois became the first ship to pass through the locks at Sault Ste. Marie, which connect Lakes Huron and Superior via the St. Mary’s River. Workers spent two years building two 350-foot locks, which allow vessels to navigate the twenty-one-foot difference between the lakes. The state of Michigan operated the locks until 1881 when the federal government took control. Today, the locks are the world’s busiest and carry more annual tonnage than the Panama and Suez Canals combined. By 1997, the total tonnage locked through “The Soo” was nearly 8.4 billion tons. Between 1987 and 1996, the average annual tonnage was 85.5 million tons.
Source : Michigan Historical Calendar, Clarke Historical Library at Central Michigan University.