The Soo Locks in Sault Ste. Marie in Michigan’s Upper Peninsula are operated and maintained by the U.S. Army Corps of Engineer. The name came from Father Jacques Marquette, a French Jesuit missionary. With this name Father Marquette was honoring Sainte Marie, a nod to Mary, mother of Jesus. Sainte is the feminine version of Saint. In an older version of French, sault translates to rapids. Father Marquette was naming the town of the geographical feature of the area: the rapids of Saint Mary.

They are a set of parallel locks that make ships travelling between Lake Superior and Lower Great Lakes possible. The locks bypass the rapids where the water falls 21 feet on the St. Marys River.

Located between Lake Superior and Lake Huron on the St. Marys River between Michigan’s Upper Peninsula and the Canadian province of Ontario. The Sault Ste Marie International Bridge connects Canada and the United States and passes over the locks. A railroad bridge connecting the two countries is located upstream of the highway bridge.

Soo Locks History

The only waterway between the lower Great Lakes and Lake Superior is the St. Marys River. The river drops 21 feet in over a ¾ mile set of rapids over hard sandstone. These rapids made it impossible for vessels to pass through. To move contents into or out of Lake Superior the vessels were unloaded, and contents portaged around.

In 1797 to provide passage for trade canoes, the first lock was constructed on the Canadian side of the St. Marys River. It was constructed by the Northwest Fur Company for small boats and was 38 feet long.

During the war of 1812 American forces destroyed the lock. Cargo once again had to unloaded and hauled over land and then reloaded on vessels.

State Lock 1855 – 1888

In 1853 the State of Michigan put out to contract building new locks on the U.S. side of the river. The project had specific requirements and a two-year deadline and was financed by a congressional land grant of 750,000 acres. E&T Fairbanks (Fairbanks Scale Company) was a Vermont company that invested in mineral resources in the state and won the contract. Charles T. Harvey was tasked with overseeing the construction of the locks and meeting the specifications and two-year timeline. Two locks were constructed with each chamber measuring 350 feet long, 70 feet side and 12 feed deep with a lift of 9 feet. Quite an ambitious undertaking by the State of Michigan and E&T Fairbanks. It was completed on time and in 1855 ships were once again able to transport between the two Great Lakes easily.

The locks were operated and maintained by the State of Michigan. As shipping traffic grew and vessels were getting bigger, a larger lock was needed. With no resources to construct new locks the State reached out to the Federal government.

Weitzel Lock 1881

The State of Michigan passed legislation to turn the locks over to the Federal government. The operation of the lock at the Soo was too important to the nation not to be properly managed and maintained.

The Federal government was slow to accept the responsibility. The government did not formally accept ownership and management of the facility for several years. Congress appropriated funds to build a new, larger lock before formally accepting ownership and management of the facility.

The Weitzel Lock was 515 feet long, 80 feet wide and 17 feed deep with a lift of 20 feet. The Weitzel lock was different from the State Lock in the way water was passed through the locks. The State Lock was filled and emptied through sluices in the gates. The Weitzel Lock filled and emptied through openings in its floor. This reduced turbulence in the lock. This method has been used for every lock built as the Soo since.

Weitzel Lock was formally turned over to the Federal government upon its completion. The U.S. Army Corps of Engineers have operated and maintained the Soo Locks ever since.

Poe Lock 1896 (first)

Work began on building a larger lock to replace the outdated State Lock six year after the opening of the Weitzel Lock. Ships kept getting bigger and traffic kept increasing creating log wait for the Weitzel Lock.

Earlier Locks had gates made of wood, the Poe Lock would have lock gates made of steel. The first lock on the St. Marys River to have steel gates. Measuring 800 feet long, 100 feet wide and 21 feet deep, the Poe Lock eased congestion entering and leaving Lake Superior.

Davis Lock 1914

The Poe Lock’s capacity was pushed to the limits in the early part of the 20th century. It was designed to lock up to four ships at a time. By 1905 ships were being built up to 569 feet long and had to be locked through one at a time. In 1911 boats passed the 600 feet mark with the Col. James M Schoonmaker that was launched at 613 feet. This started created lengthy delays at the locks.
A new lock was needed. The Davis Lock was built in 1914 at 1,350 feet long, 80 feet wide and 24 feet deep.

Sabin Lock 1919

Traffic at the locks continued to grow as did the length of boats in the Great Lakes. In 1913 a fourth lock was approved, and work began a year before the completion of the Davis Lock. Both the Davis and Sabin locks were built using the same plans. They were also another first for the Soo Locks. Both locks were built with concrete walls, unlike the stone masonry used on previous locks. Electric winding machines were used to open and close the gates.

MacArthur Lock 1943

After 1919 the Weitzel Lock saw little use with three newer and larger locks operating. The channels in the St. Marys River had been deepened to 24 feet by 1936. Shipping companies were wanting a new lock that was deeper and could operating with deeper and deeper drafts.
Construction of a new lock to replace the Weitzel was approved in March 1942. With the U.S. drawn into WWII, the need for a steady supply of iron ore to steel mills were a matter of national security. Construction of the MacArthur Locks were completed in less than two years.

Poe Lock 1968 (second)

By the 1950s larger vessels were pushing the limits of the locks, even the relative new MacArthur Lock could not meet the growing demands.
In 1958 planning was started for a bigger and deeper lock that would replace the 60+ year old original Poe Lock. Construction began in 1961 for a lock 1000 feet long and 100 feet wide.
Early into the project the lock was redesigned as it became clear that an even larger lock was needed. The new design made the locks it current 1200 feet long and 110 feet wide. In 1968 a trial ship went through and in 1969 the lock opened for commercial traffic. In less than four years the first 1000-foot-long ship on the Great Lakes passed through the Poe Lock.

Below are some fun facts about the Soo Locks originally published in Adventures In Northern Michigan on August 24, 2022.

Did you know?

20 things about the Soo Locks

Called the “Linchpin of the Great Lakes” by the United States Army Corps of Engineers, this engineering marvel has roots that date back to the mid 1800’s. The Soo Locks are a National Historic Site in Michigan’s oldest city.

1. Did you know that 90% of iron ore passes through the Soo Locks annually? The value is over $500 billion.

2. Did you know that you can take your personal boat through the Soo Locks? You have to have a motor and permission from the lockmaster.

3. Did you know that about 12,000 vessels pass through the locks yearly? Crews complete these during the 42 weeklong navigation seasons, they are open 24 hours a day.

4. Did you know that the Soo Locks are part of the St. Lawrence Seaway? Ships from all over the world visit this port as the locks which help connect Duluth, Minnesota to the Atlantic Ocean. Duluth is 2,332 miles from the Atlantic Ocean and takes on average 7 days to reach it from Duluth.

5. Did you know that 22 million gallons of water are required to traverse a boat through the Poe Lock? There are no pumps, the locks are powered by gravity. Water moves in and out of the lock chambers by opening and closing valves.

6. Did you know that the largest boat that goes through the Soo Locks is over 1,000 feet long? The largest boat is the Paul R. Tregurtha at 1,013 feet 6 inches. There are 13 – 1,000 footers on the Great Lakes.

7. Did you know that it takes 9 hours to pass through the Soo Locks. The time between Lake Superior and Lake Huron it takes a freighter about 9 hours to pass through the St. Mary’s River System.

8. Did you know that a thick layer of bedrock (the same stone that makes Pictured Rocks) holds back the waters of Lake Superior where it joins the St. Mary’s River? This drop prevents boats from passing through. The reddish sandstones lines most of Lake Superior Southern shores and is about 1000 feet thick.

9. Did you know that the Soo Locks are toll free? From 1855 to 1881 the toll was 3-4 cents per ton. In 1881, the locks were transferred to the U.S. government and placed under the jurisdiction of the U.S. Army Corps of Engineers. The Corps have operated it toll-free since.

10. Did you know that the propeller in Soo Locks Park is from a steamer named Independence? This steamer exploded just northwest of today’s locks. One crew member is said to have survived a trip down the rapids on a bale of hay from the ship.

11. Did you know that the locks are open from late March through Mid-January depending on the weather? – It is estimated that 500,000 people visit the Soo Locks and watch the freighters go through the locks up close.

12. Did you know that you can take a boat tour of the Soo Locks? There are a couple of companies that provide tours that let you experience both an up bound and down bound lockage.

13. Did you know that the Poe Lock is the lock that most ships use? It is 1,200 feet and was originally completed in 1896 and rebuilt in 1968 to accommodate larger and more modern ships.

14. Did you know that the MacArthur Lock at 800 feet is still in operation? It was constructed in 1943 and is name after General Douglas MacArthur. It is the lock closest to Sault Ste. Marie and the observation deck in the Soo Locks Park overlooks it.

15. Did you know that a lock was constructed in 1797 on the Canadian side of the river. The Northwest Fur Company constructed it for small boats and it was 38 feet long. The lock remained in use until it was destroyed in the War of 1812.

16. Did you know that freighters and boats were portaged around the rapids after the first lock was destroyed in the War of 1812? The Fairbanks Scale Company who had mining interests in the Upper Peninsula agreed to the project of building a new lock in 1853. The first chamber built was the State Lock in 1855 and once again ships were able to easily transport between the two great lakes.

17. Did you know that there are 5 locks? The MacArthur (built 1943), the Poe (built 1896), the Davis (built 1914), the Sabin (built 1919) and the Canadian. The Canadian is for pleasure craft only, the Davis is for Soo Area Office Vessels and the Sabin is closed.

18. Did you know that there is a 21-foot difference in elevation between Lake Superior and Lake Huron? This creates a ¾ mile set of rapids over sandstone that blocked shipping freighters before the canal and locks were built.

19. Did you know that the Soo Locks makes its own electricity? They only use about 5% of what they make and sell the excess to the local power utility.

20. Did you know that the St. Marys River is dammed? The hydro plants, locks, and other works above the rapids acts as a dam to regulate the water flowing out of Lake Superior. An international treaty signed in 2910 with Great Britain governs water use. Canada has replaced Great Britain in this treaty.

Learn more about the rich history of the Eastern Upper Peninsula.