Over the weekend, some 360 workers at the St. Lawrence Seaway Management Corporation walked off the job. The Seaway is a system of locks, canals and channels that connects the Great Lakes to the St. Lawrence River and eventually, the Atlantic Ocean, allowing cargo ships to get in and out of the middle of North America. 

Last year, about $13 billion worth of cargo passed through the Seaway. So, what does the strike mean for industries that rely on that shipping artery? 

The Seaway was built by the U.S. and Canadian governments in the 1950s to connect the upper Midwestern states and prairie provinces to global markets.

“The St. Lawrence Seaway is a main artery,” said Michael Folsom with the Seaway Ship Watchers Network. 

And he said it can’t function without those striking workers who are looking for wage increases. 

“It’s almost a chokehold, from Montreal to Lake Eerie,” he said.

In Canada, the biggest worry is how farm economies will fare during the strike, said Sylvain Charlebois, a professor of agribusiness at Dalhousie University in Halifax.  

“Our estimate there’s about six or seven billion dollars worth of grain that are exported from the St. Lawrence Seaway” every year, he said, mostly to Europe and the Middle East. 

Charlebois said this disruption comes just as Canadian wheat farmers are looking to ship their harvests.

“We’re in the middle of October here,” he said. “We need to move product.”

And while the war in Ukraine and extreme weather around the world are also squeezing the global grain supply, Charlebois said the Seaway’s closure could drive up commodity prices. 

“And that impacts the entire world,” he said.

The strike is also a headache for manufacturing in the middle of the continent, said Steven Fisher with the American Great Lakes Ports Association. 

The U.S. and Canadian auto industries are largely domiciled there, and the majority of U.S. steel production happens in the Great Lakes region, relying on iron ore imported via the St. Lawrence Seaway. 

Fisher said if the strike goes on much longer, all the goods that typically come in and out of the region by ship will have to be put on wheels — a costlier and less climate-friendly option.