Color postcard from 1928 of the view of the Davis Lock from the bow of a ship entering it in Sault Sainte Marie, Michigan. The caption of the postcard describes this lock as "1350 feet long and 80 feet wide (the longest lock in the world)." It is the same length as the neighboring Sabin Lock. The postcard is part of a Sault Sainte Marie souvenir postcard booklet. 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.