Soo Locks

The Soo Locks (sometimes spelled Sault Locks, but pronounced "soo") are a set of parallel locks which enable ships to travel between Lake Superior and the lower Great Lakes. They are located on the St. Mary’s River between Lake Superior and Lake Huron, between the Upper Peninsula of the US state of Michigan and the Canadian province ofOntario. They bypass the rapids of the river, where the water falls 21 feet (7 m). The locks pass an average of 10,000 ships per year,[4] despite being closed during the winter from January through March, when ice shuts down shipping on the Great Lakes. The winter closure period is used to inspect and maintain the locks.

The locks share a name (usually shortened and anglicized as Soo) with the two cities named Sault Ste. Marie, in Ontario and Sault Ste. Marie in Michigan, located on either side of the St. Marys River. The Sault Ste. Marie International Bridge between the United States and Canada permits vehicular traffic to pass over the locks. A railroad bridge crosses the St. Marys River just upstream of the highway bridge.

United States locks
The U.S. locks form part of a 1.6-mile (2.6-km) canal formally named the St. Marys Falls Canal. The entire canal, including the locks, is owned and maintained by the United States Army Corps of Engineers, which provides free passage. The first iteration of the U.S. Soo Locks was completed in May 1855; it was operated by the State of Michigan until transferred to the U.S. Army in 1881.

The current configuration consists of four parallel lock chambers, each running east to west; starting at the Michigan shoreline and moving north toward Ontario, these are:
 * The MacArthur Lock, built in 1943. It is 800 feet (244 m) long, 80 feet (24 m) wide, and 29.5 feet (9 m) deep.[5] This is large enough to handle ocean-going vessels ("salties") that must also pass through the smaller locks in the Welland Canal. The first vessel through was the SS Carl D. Bradley.

The lock was re-built in 1968 to accommodate larger ships, after the Saint Lawrence Seaway opened. It is 1,200 feet (366 m) long, 110 feet (34 m) wide, and 32 feet (10 m) deep.[5] It can take ships carrying 72,000 tons of cargo. The Poe is the only lock that can handle the large lake freighters used on the upper lakes. The first passage after the rebuild was by the Phillip R. Clarke in 1969.[7]
 * The Poe Lock, originally completed on August 3, 1895. The first ship to pass through was the passenger ship Majestic in September 1895.[6] The original Poe Lock was engineered by Orlando Poe and, at 800 feet long and 100 feet wide (244 x 30 m), was the largest in the world when completed in 1896.[7]
 * The Davis Lock, built in 1914. It is 1,350 feet (411 m) long, 80 feet (24 m) wide, and 23.1 feet (7 m) deep.[5] This lock is used less frequently (only 5 commercial/private and 34 government vessel passages, on 14 days in October 2008[8]) to lock light freighters, tour boats, and small craft when traffic warrants. The SS James A Farrell was the first vessel to lock through.[citation needed]

The Davis and Sabin locks have been slated for replacement since 1986 with a new ' Super-Lock' , which would provide a second lock capable of accommodating the "lakers".[5] Groundbreaking for the new lock project was held on June 30, 2009, although the bulk of the funding necessary to complete the project has not yet been appropriated by Congress.[9] This construction will further limit usage of the Davis Lock.
 * The Sabin Lock, built in 1919. It is 1,350 feet (411 m) long, 80 feet (24 m) wide, and 23.1 feet (7 m) deep.[5] This lock has been placed in caretaker status and is no longer used. To get the Sabin lock up and running again would cost roughly 5 million dollars.[citation needed]

North of the Sabin Lock is an additional channel with a small hydroelectric plant, which provides electricity for the lock complex. 2008 Panorama from the MacArthur Lock, facing north

Engineers Day
On the last Friday of every June, the public is allowed to go behind the security fence and cross the lock gates of the U.S. Soo Locks for the annual Engineers Day Open House.[10][11]During this event, visitors are able to get close enough to touch ships passing through the two regularly operating locks.

Canadian lock
Main article: Sault Ste. Marie Canal

A single small lock is currently operated on the Canadian side of the Soo. Opened in 1998, it was built within a damaged older lock, and is 77 meters (253 ft) long, 15.4 meters (51 ft) wide and 13.5 meters (44 ft) deep.[12] The Canadian lock is used for recreational and tour boats; major shipping traffic uses the U.S. locks.