The Soo Locks (sometimes spelled Sault Locks but pronounced "soo") are a set of parallel locks, operated and maintained by the

United States Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wo ...

, Detroit District, that enable

ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...

s to travel between

Lake Superior Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered tw ...

and the lower

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

. They are located on the St. Marys River between Lake Superior and

Lake Huron Lake Huron ( ) is one of the five Great Lakes of North America. It is shared on the north and east by the Canadian province of Ontario and on the south and west by the U.S. state of Michigan. The name of the lake is derived from early French ex ...

, between the

Upper Peninsula The Upper Peninsula of Michigan—also known as Upper Michigan or colloquially the U.P. or Yoop—is the northern and more elevated of the two major landmasses that make up the U.S. state of Michigan; it is separated from the Lower Peninsula b ...

of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

and the

Canadian province Canada has ten provinces and three territories that are sub-national administrative divisions under the jurisdiction of the Constitution of Canada, Canadian Constitution. In the 1867 Canadian Confederation, three provinces of British North Amer ...

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

. They bypass the rapids of the river, where the water falls . The locks pass an average of 10,000 ships per year, 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 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. The first locks were opened in 1855. Along with the

Erie Canal The Erie Canal is a historic canal in upstate New York that runs east–west between the Hudson River and Lake Erie. Completed in 1825, the canal was the first navigability, navigable waterway connecting the Atlantic Ocean to the Great Lakes, ...

, constructed in 1824 in central New York State, they were among the great infrastructure engineering projects of the antebellum United States. The Soo Locks were designated a

National Historic Landmark A National Historic Landmark (NHL) is a National Register of Historic Places property types, building, district, object, site, or structure that is officially recognized by the Federal government of the United States, United States government f ...

in 1966.

United States locks

The U.S. locks form part of a canal formally named the St. Marys Falls Canal. The entire canal, including the locks, is owned and maintained by the

, 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.

Locks

The configuration consists of two parallel lock chambers.Starting at the Michigan shoreline and moving north toward Ontario, these are: *The MacArthur Lock, built in 1943. It is long, wide, and deep. This is large enough to handle ocean-going vessels ("salties") that must also pass through the smaller locks in the

Welland Canal The Welland Canal is a ship canal in Ontario, Canada, and part of the St. Lawrence Seaway and Great Lakes Waterway. The canal traverses the Niagara Peninsula between Port Weller, Ontario, Port Weller on Lake Ontario, and Port Colborne on Lak ...

. The first vessel through was the SS ''Carl D. Bradley''. Per 33 CFR § 207.440 (v), "The maximum overall dimensions of vessels that will be permitted to transit MacArthur Lock are 730 feet in length and 75 feet in width, except as provided in paragraph (v)(1) of this section." Per U.S. Army Corps of Engineers, Sault St Marie, the length of the ship is restricted to 730’ due to the southwest wall alignment entering and exiting the MacArthur Lock. *The Poe Lock, built in 1896. The first vessel to pass through was the U.S. Army Corps of Engineers tug USS ''Hancock''. The original Poe Lock was engineered by Orlando Poe and, at long and wide, was the largest in the world when completed in 1896. The lock was re-built in 1968 to accommodate larger ships, after the

Saint Lawrence Seaway The St. Lawrence Seaway () is a system of rivers, locks, canals and channels in Eastern Canada and Northern United States that permits oceangoing vessels to travel from the Atlantic Ocean to the Great Lakes of North America, as far inland ...

opened and made passage of such ships possible to the Great Lakes. It is now long, wide, and deep. It can take ships carrying of cargo. The Poe is the only lock that can handle the large

lake freighter Lake freighters, or lakers, are bulk carriers operating on the Great Lakes of North America. These vessels are traditionally called boats, although classified as ships. Freighters typically have a long, narrow hull, a raised pilothouse, and the ...

s used on the Upper Lakes. The first passage after the rebuild was by the ''Phillip R. Clarke'' in 1969.

Former locks

*The State Lock, built between 1853 and 1855. The State of Michigan was given land by the federal government to construct a lock to allow for quicker transit of new

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

and

iron ore Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the f ...

deposits discovered around the Lake Superior basin. The lock consisted of two chambers back-to-back to bridge the difference in water level. Each chamber was long, wide at the top of its walls and at its bottom, and deep. The State Lock was replaced by the original Poe Lock in 1896. *The Weitzel Lock, was built between 1873 and 1881 directly south of the State Lock, and was the first lock to be operated by the federal government. At long, wide, and deep, it was the longest lock in the world upon its completion. It was decommissioned in 1919, and was eventually replaced by the MacArthur Lock in 1943. *The Davis Lock, built in 1914. At the time of its completion, the Davis Lock was the longest lock in the world at long, and was also wide and deep. It was officially decommissioned in 2010. *The Sabin Lock, built in 1919. It was constructed as a twin lock to the Davis Lock, and named after Louis Carlton Sabin (1867-1950), the designer of both locks, who served as General Superintendent of the ship canal at The Soo from 1906 to 1925. It was officially decommissioned in 2010 at the same time as the Davis Lock.

New lock

A new lock is under construction and is slated to be completed by 2030. Groundbreaking for the new lock project was held on June 30, 2009. The lock will be equal in size to the Poe Lock and will provide much needed additional capacity for the large lake freighters. The new lock replaces two locks (Davis Lock and Sabin Lock), which were obsolete and used infrequently. In May 2020, construction on Phase One of the replacement of the Sabin Lock was started. North of the new lock is an additional channel with a small hydroelectric plant, which provides electricity for the lock complex.

Engineers Day

The U.S. Army Corps of Engineers, Detroit District, operates the Soo Locks Visitors Center and viewing deck for the public. 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. During this event, visitors are able to get close enough to touch ships passing through the two regularly operating locks. Other than on that day, because the locks are United States Federal property under command of the U.S. Army Corps of Engineers, unauthorized personnel and civilians are restricted from the locks under threat of fines or imprisonment for trespassing.

Canadian lock

The first lock to be built in the St. Marys River was on the Canadian side in 1798 by the Northwest Fur Company to facilitate the

fur trade The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal ecosystem, boreal, polar and cold temperate mammalian animals h ...

. It was destroyed by the Americans in 1814 during the

War of 1812 The War of 1812 was fought by the United States and its allies against the United Kingdom of Great Britain and Ireland, United Kingdom and its allies in North America. It began when the United States United States declaration of war on the Uni ...

to disrupt British trade. Currently, a single small lock is operated on the Canadian side of the Soo. Opened in 1895, it was rebuilt in 1987, and is long, wide and deep. The Canadian lock is used for recreational and tour boats; major shipping traffic uses the U.S. locks.

Gallery

File:Soo Locks 19th Century.jpg, The first Soo Locks in the 19th century File:Anchor Line Steamer in the Locks (NBY 9947).jpg, Anchor Line steamer in the Soo Locks, ca. 1900s File:PoeLock whaleback MHGL00371f.jpg, A

whaleback A whaleback was a type of cargo steamship of unusual design, with a hull that continuously curved above the waterline from vertical to horizontal. When fully loaded, only the rounded portion of the hull (the "whaleback" proper) could be seen a ...

traverses the Poe Lock, ca. 1910 File:Sault canal NHS adjusted.jpg, Canadian Lock at Sault Ste. Marie, Ontario File:Poe Lock - 2014.jpg, The last ship of the 2013 season passes through the Poe Lock File:USCGC Mackinaw passes through Soo Locks 130314-G-ZZ999-001.jpg, USCGC ''Mackinaw'' passes through Soo Locks

References

*33 CFR 207.440 *33 CFR 207.441

External links

Soo Locks homepage
U.S. Army Corps of Engineers Soo Locks page
Web Camera
view of the American locks NOTE: This Connection is Untrusted
Animation of how the Soo Locks work

YouTube video
HD video of a ship passing through the MacArthur Lock {{Authority control Canals in Michigan Locks of the United States Locks on the National Register of Historic Places Great Lakes Waterway Ship canals St. Marys River (Michigan–Ontario) Buildings and structures in Sault Ste. Marie, Michigan Michigan State Historic Sites in Chippewa County National Historic Landmarks in Michigan Canals on the National Register of Historic Places in Michigan Transportation in Chippewa County, Michigan National Register of Historic Places in Chippewa County, Michigan Transportation buildings and structures on the National Register of Historic Places in Michigan Transportation buildings and structures in Michigan 1855 establishments in Michigan United States Army Corps of Engineers Canada–United States border