Color cover of the 1920 "Souvenir of the Tourist Playground of Cloverland, Soo, Mich." souvenir postcard booklet, featuring an automobile, train, and a ship moving through the Soo Locks. The Soo Locks, located on St. Marys River between the United States and Canada, provide ships safe passage around the rapids in the canal. The first locks in this canal were built in 1855, and have been improved upon ever since. The locks are the busiest, based on tonnage passing through, in the world.
