The Army Corps of Engineers finished its yearly maintenance of the Soo Locks early this year, letting the new Poe Lock open a few days ahead of schedule.
About 7,000 ships move through the Soo Locks each year for transport and trade. According to the U.S. Army Corps of Engineers, almost all of the country’s iron ore travels through the locks.
Daniel Rust, associate professor of transportation and logistics management at the Univetsity of Wisconsin-Superior and director of its School of Business and Economics, told WPR’s “Wisconsin Today” the companies that rely on the Soo Locks can get a jump start on their shipping season now.
Stay informed on the latest news
Sign up for WPR’s email newsletter.
“The Soo Locks are the only way in and out of Lake Superior,” Rust said. “It is a vital lifeline for the Great Lakes and for our region.”
Rust also discussed future improvements for the locks and how new federal tariffs may affect what goes through them locks this year.
The following was edited for clarity and brevity.
Lee Rayburn: What do the Soo Locks do?
Daniel Rust: The Soo Locks date way back into the 1800s when they were first developed. There’s about a 21-foot difference between Lake Superior and the lake below, so it’s needed to somehow get vessels up over that difference, so the Soo locks were developed. Currently there are two. There’s the smaller MacArthur lock, and then the larger Poe Lock which handles the largest vessels that transit the Great Lakes.
The Poe Lock opened this (Friday) morning. It is 1,200 feet long and could handle any of the vessels on the Great Lakes. The MacArthur lock will probably open sometime in April next month.
LR: Why do the four locks close? When does that happen for the season?
DR: By federal regulation, the locks close on Jan. 15. This gives certainty to all stakeholders to know when they will close and approximate when they will open. The regulations have been amended many times since the 1950s and have actually been extended. Originally, it would close in mid-December until April.
LR: What does it take to open the locks?
DR: Ice is a factor, but the predominant factor is that the Army Corps of Engineers, who maintain and operate the locks, were able to complete the maintenance they’ve been doing on the lock early. And so they were able to accommodate a request from the lake carriage association to open a lock a little bit early.
LR: What’s the maintenance look like for these locks?
DR: Mostly the maintenance consists of repairing machinery and making sure that it’s all functioning properly. It’s vital to have the locks, particularly the Poe, operational throughout the season. If the Poe were to, for some reason, go down during the season, it would be catastrophic for not just the regional economy, but the nation as a whole, particularly because of the iron ore that travels from Lake Superior to the lower lakes.
LR: What do we know so far about how tariffs that are being proposed by President Trump could affect the shipping in the Great Lakes?
DR: It definitely could have an impact. It probably already has. The Cleveland Cliffs announced that they’re going to be idling a mine up on the Iron Range in Minnesota because they have an excess of taconite (a low grade iron ore) ready to go.
With the threat of tariffs and the slowdown of auto manufacturing, demand for steel has declined. As they anticipate continued lower demand, the supply needed will be less, which also then translates into less being transported on the Great Lakes and lower need for vessels moving those tonnages.
LR: During the first Trump administration, the President approved federal funding for the Poe Lock in hopes it would help the shipping industry in the Great Lakes. What are you monitoring in terms of federal actions and shipping on the Great Lakes?
DR: So far, there seems to be a clear consensus that it’s a priority to build a second Poe-sized lock. It’s under construction currently. It started about four years ago. It’s a $3 billion project and requires a lot of federal money to make this happen.
Some might say, “Why do we need a second 1,200-foot lock?” If the current Poe Lock went down during a season, it would be catastrophic. We need to have some resilience built into the system, and having a second lock that of similar size would allow that. And so far, it seems like most all stakeholders are in agreement that we need to move forward and continue to fund the second 1,200 foot lock. It is set to open in 2031.
Wisconsin Public Radio, © Copyright 2025, Board of Regents of the University of Wisconsin System and Wisconsin Educational Communications Board.
