DULUTH — The Soo Locks, a gateway on the St. Marys River between Lake Superior and the lower Great Lakes, will open on the evening of March 22 — kicking off the 2024 shipping season three days earlier than originally planned.

The shipping industry was nudged by major steel producers to jump-start the kickoff. Even a day can make a difference in keeping blast furnaces operating at full capacity, according to Jayson Hron of the Duluth Seaway Port Authority.

"At this time of year, Great Lakes steelmaking facilities are especially hungry for iron ore," he said. "That demand, along with a lack of ice cover, was the catalyst for the industry's request to open the Soo Locks early."

The Soo Locks initially were scheduled to open March 25. The St. Lawrence Seaway announced in mid-February that it would open on March 22 and the Lake Carriers' Association president asked to follow suit on the Soo.

Its president, James Weakley, noted that the 2023 season was stalled by a more than weeklong strike when 350 workers walked off the job. Extreme winds at the end of the operating season also left the fleet with undelivered cargo, he said in a news release from the U.S. Army Corps of Engineers Detroit District.

The winter shutdown included critical repairs to the Poe Lock and the lesser used MacArthur Lock, the two locks that are operational at the Soo Locks in Sault Ste. Marie, Mich. According to the U.S. Army Corps of Engineers, there were structural inspections and maintenance, work on the miter gates that serve as dams and the systems that control the drift of the ships as they pass through.

Maintenance branch chief Nicholas Pettit said crews worked extended hours and were helped along by mild weather.

"We've been able to accomplish all required work ahead of schedule," he said.

The MacArthur Lock still is undergoing maintenance. It will reopen on April 24.

The 2023 season was considered a very good one for the Port of Duluth-Superior, helped along by 21.5 million tons of iron ore that came through — the most in a single season since 1995, the port authority said in its season wrap-up. The international shipping season was 277 day, the longest in port history, and the Great Lakes season was 305 days.

Eight vessels spent the winter in Duluth-Superior — the most since the winter of 2016-17. The lineup included the Paul R. Tregurtha, Baie Comeau, John G. Munson, Lee A. Tregurtha, Manitoulin, Arthur M. Anderson, John Boland and American Spirit.

Hron said some local ships likely will start loading iron ore the week of March 18, then queue up to pass through the Soo Locks right when they open. The same will be happening for upbound ships headed to Lake Superior.

"Those giant stockpiles of iron ore visible alongside Interstate 35 in West Duluth will begin moving from shore to ship, destined for steelmaking facilities on the lower Great Lakes," Hron said.