The Soo Locks: Twenty-One Feet Between Lakes

Lake Superior sits twenty-one feet higher than Lake Huron. The St. Marys River drops those twenty-one feet in about a mile of rapids at Sault Ste. Marie. For centuries, this was the passage between the eastern and western Great Lakes, and for centuries everything that moved between them had to be portaged around the rapids by hand, canoe by canoe, cargo by cargo. The Anishinaabek called this place Baawitigong, the place of the rapids.

The first American lock at Sault Ste. Marie opened in eighteen fifty-five. The modern system that operates today handles roughly eight thousand vessels per year carrying over eighty million tons of cargo, primarily iron ore from the Marquette Range bound for the steel mills of Cleveland, Pittsburgh, and Detroit, along with coal, grain, and limestone moving in the opposite direction. For decades in the mid-twentieth century, more tonnage passed through these locks than through the Panama Canal.

The mechanism is elegantly simple: a ship enters a chamber, gates close, water is pumped in or drained out by gravity alone, the ship rises or falls twenty-one feet, the far gates open. No pumps for lifting, only for draining. The water does the work. A transit takes roughly forty-five minutes. When the locks are closed for winter maintenance, the economic consequences are felt in steel plants from Ohio to Indiana.

The American steel economy runs through this channel. It always has.