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Soo Locks

St. Marys Falls Canal
Aerial view of the Soo Locks. View is to the east, with Canada on the left and the United States on the right
Soo Locks is located in Michigan
Location Sault Ste. Marie, Michigan
Built 1837
Architect Corps of Engineers
Architectural style No Style Listed
NRHP Reference # 66000394[1]
Significant dates
Added to NRHP November 13, 1966
Designated NHL November 13, 1966[2]
Designated MSHS February 12, 1959[3]
The last ship of the 2013 season passes through the Poe Lock
The first Soo Locks in the 19th century
A whaleback traverses the Poe Lock, ca. 1910

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. Marys River between Lake Superior and Lake Huron, between the Upper Peninsula of the US state of Michigan and the Canadian province of Ontario. 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 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 1
    • Engineers Day 1.1
  • Canadian lock 2
  • References 3
  • Further reading 4
  • External links 5

United States locks

The U.S. locks form part of a 1.6 miles (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 (240 m) long, 80 feet (24 m) wide, and 29.5 feet (9.0 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 Poe Lock was 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 (240 m) long and 100 feet (30 m) wide, was the largest in the world when completed in 1896.[7] The lock was re-built in 1968 to accommodate larger ships, after the Saint Lawrence Seaway opened. It is now 1,200 feet (370 m) long, 110 feet (34 m) wide, and 32 feet (9.8 m) deep.[5] It can take ships carrying 72,000 short tons (65,000 t) 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 Davis Lock, built in 1914. It is 1,350 feet (410 m) long, 80 feet (24 m) wide, and 23.1 feet (7.0 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.
  • The Sabin Lock, built in 1919. It is 1,350 feet (410 m) long, 80 feet (24 m) wide, and 23.1 feet (7.0 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.

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.

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

Canadian Lock at Sault Ste. Marie, Ontario

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.


33 CFR 207.440 33 CFR 207.441

  1. ^ "National Register Information System". National Register of Historic Places.  
  2. ^ "St. Marys Falls Canal". National Historic Landmark summary listing. National Park Service. Retrieved 2008-06-27. 
  3. ^ State of Michigan (2009). "Saint Mary's Falls Canal". Retrieved June 26, 2010. 
  4. ^ "USACE – Detroit District – Facts". Retrieved 2008-10-22. 
  5. ^ a b c d e David Helwig (March 30, 2002). "$227 million lock replacement could start this year". 
  6. ^ Arbic (and Nancy Steinhaus), Bernard (2005). Upbound Downbound: The Story of the Soo Locks. Allegan Forest: Priscilla. pp. 35–37. 
  7. ^ a b Seeing The Light - Orlando Metcalfe Poe. (2000-05-30). Retrieved on 2012-04-10.
  8. ^ U.S. Army Corps of Engineers, Traffic Statement: 2008 Navigation Season, p. 3, retrieved 2009-08-30 
  9. ^ "Construction beginning on new Soo shipping lock".  
  10. ^ "USACE – Detroit District – Soo Locks – Sault Ste- Marie". U.S. Army Corps of Engineers. Retrieved 2011-03-05. 
  11. ^ "Soo Locks Engineer's Day". 2010-06-24. Retrieved 2011-03-05. 
  12. ^ Sault Ste. Marie Canal National Historic Site of Canada, Natural Wonders & Cultural Treasures, Parks Canada.

Further reading

  • Taylor, Paul (October 2009) Orlando M. Poe: Civil War General and Great Lakes Engineer (Kent State University Press) ISBN 1-60635-040-4; ISBN 978-1-60635-040-9.

External links

  • Aerial views
  • 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
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