The Soo Locks

A wonder of engineering and human ingenuity


Affectionately called the “Linchpin of the Great Lakes” by the United States Army Corps of Engineers, the Soo Locks are an engineering marvel with roots dating back to the mid-1800s. Each year it’s estimated that 500,000 people visit these iconic locks that connect Lakes Superior and Huron.

(The above image links to a 360-degree virtual reality video on YouTube. Use your mouse to move it around or try it out with a smartphone!)

Thanks to the Soo Locks freighters over 1,000 feet in length can traverse freely along the St. Marys River all the way from Duluth, Minnesota outward into the Atlantic Ocean and beyond. Roughly 7,000 vessels pass through the Locks yearly hauling nearly 86 million tons of cargo. See how freighters, barges, tugboats and more are lifted and lowered the 21-foot difference between Superior and Huron here.

Most ships utilize the Poe Lock (1,200 feet) which was rebuilt in 1968 to accommodate larger and more modern ships. The MacArthur Lock (800 feet), constructed in 1943, is still in operation as well. It is the lock closest to Sault Ste. Marie, which the observation deck in the Soo Locks Park overlooks, and was named after General Douglas MacArthur. The Davis and Sabin Locks were built in 1914 and 1919 respectively. Currently, only Soo Area Office vessels use the Davis while the Sabin was officially decommissioned in 2010 after being inactive since 1989.

Wondering when the next ship will pass through? Call the Vessel Recording line: (906) 253-9290

For information off-season please call the Sault Ste. Marie Convention & Visitors Bureau: (906) 632-3366

Looking to see when the next freighter will pass through the Soo Locks? Check out our handy guide.

See the Ships & Explore the Park

Spectators stand on the Soo Locks Observation Deck to watch sailboats from the 2019 Trans Superior International Yacht Race lock into Lake Superior.

Take in the sights, sounds and vibrating feelings of being up close and personal with some of the Great Lakes largest freighters with the observation platform located in the Soo Locks overlooking the MacArthur Lock. The Soo Locks aren’t just for mammoth lake freighters either. Catch unique vessels such as tall ships, sailboats, cruise ships, and military crafts lock into Lake Superior or Huron.

The Soo Locks Park has many great vantage points to take in the sights of the historic locks too. A few steps from the water’s edge the park boasts shady grass, defined walkways, manicured gardens and democracy of trees representing those found throughout the Upper Peninsula.

Also on the grounds, the historic 1899 US Weather Bureau Building houses the administrative office home of the Great Lakes Shipwreck Historical Society. Open year-round, the building offers a public exhibit, museum store sales area and access to the Shipwreck Society’s noted Great Lakes Images and Papers Collection.


Fun Facts

This animated illustration explains how lock systems work. (Gif courtesy of the United States Army Corps of Engineers)

  • 90% of the world’s iron ore moves through the Soo Locks
  • Learn how the Soo Locks work HERE.
  • Duluth Minnesota to the Atlantic Ocean (St Lawrence Seaway) is 2342 miles or 7 days
  • Soo Locks have no pumps they are 100% gravity fed
  • Poe Lock requires 22 million gallons of water to lift or lower a boat
  • The Soo Locks close from January 15-March 25 each year for repairs per federal orders
  • It would take 584 train cars to move 70,000 tons of cargo or just one 1000 foot freighter
  • The Paul R. Tregurtha is the largest freighter on the Great Lakes at 1013.5 feet
  • The bedrock at the Soo locks is 1,000 feet thick and the type of rock is Reddish Sandstone

The First Locks

The first Soo Lock

(Photo courtesy of the United States Army Corps of Engineers)

During the region’s earliest days, the Ojibway Indians who lived nearby portaged their canoes around the “Bawating” (rapids) to reach Lake Superior from the St. Marys River.

When the settlement of the Northwest Territory brought increased trade and large boats it became necessary to unload the boats haul the cargoes around the rapids in wagons and reload in other boats.

In 1797, the Northwest Fur Company constructed a navigation lock 38 feet long on the Canadian side of the river for small boats. This lock remained in use until destroyed in the War of 1812. Freighters and boats were again portaged around the rapids.

Congress passed an act in 1852 granting 750,000 acres of public land to the State of Michigan as compensation to the company that would build a lock permitting waterborne commerce between Lake Superior and the other Great Lakes. The Fairbanks Scale Company, which had extensive mining interests, in the upper peninsula, undertook this challenging construction project in 1853.

The State Lock was the first chamber built-in 1855. Thanks to the State Lock the 21-foot difference in water levels was tamed, and easy transport between the two Great Lakes became possible. 

The Federal Government and the Soo Locks



The Federal Government took control of the property and the lock system in the 1870s. Boats that passed through the State Lock were required to pay a toll of four cents per ton until 1877 when the toll was reduced to three cents.

Within a few years, commerce through the canal had grown to national importance and the need for new locks became clear. The funds required exceeded the state’s capabilities and in 1881, the locks were transferred to the United States government and were placed under the jurisdiction of the U.S. Army Corps of Engineers. The Corps has operated the locks toll-free since that time.

The Weitzel Lock opened in 1881 and control of the Soo Locks was handed over to the US Corps of Engineers. The original Poe Lock, named after Orlando Poe, was completed in 1896.

Please read!

This site uses "Cookies" to store limited information required to provide you with a consistent user experience. Click "Show more" for additional information.

Show more Got it!