The Lock Behind 88% of U.S. Steel Ore Is Getting a $2.6 Billion Backup

Every year, roughly 46 million tons of iron ore leave the docks of Lake Superior bound for steel mills on Lakes Michigan, Erie, and Huron.▸ All of it — plus the coal and limestone that come back the other way — passes through one set of locks at Sault Ste. Marie, Michigan, connecting Superior to the rest of the Great Lakes. And within that system, one chamber does almost all the work: the Poe Lock, rebuilt to its current size in 1968, is the only one of the four locks at the Soo large enough to pass a modern 1,000-foot laker. The Army Corps of Engineers says 88 percent of the tonnage that moves through the Soo Locks is restricted to vessels that only the Poe Lock can handle — and 95 percent of domestically produced high-strength steel uses ore that transits the Soo Locks system at all. There is no second Poe-sized lock. There has not been one for 58 years.

In October 2015, the Department of Homeland Security's Office of Cyber and Infrastructure Analysis published a study most Americans have never heard of: The Perils of Efficiency: An Analysis of an Unexpected Closure of the Poe Lock and Its Impact.▸ Modeled by Sandia National Laboratories using the REMI economic-impact system, the report asked one question: what happens if the Poe Lock goes down, without warning, for six months?

The report's own words: an unexpected closure "would be catastrophic for the Nation."▸ Within two to six weeks, it found, about 75 percent of U.S. integrated steel production would cease. Nearly 100 percent of North American production of appliances, automobiles, construction equipment, farm equipment, mining equipment, and railcars — all downstream of that steel — would follow. First-year economic output would fall by $1.1 trillion, and 10.9 million people in the United States would likely be unemployed, with millions more idled in Canada and Mexico. Modeled nationally, that pushes the unemployment rate from its 2015 level of 5.5 percent to 11.3 percent — a full percentage point past the worst month of the 2008–09 recession.

The damage would not fall evenly.▸ DHS modeled which state's steel mills could keep running on ore stockpiles and alternate, smaller-capacity routes, and which would go dark entirely. Indiana's three mills around Gary — Indiana Harbor, Gary Works, and Burns Harbor, together roughly half of U.S. integrated steel capacity — would fully stop, the report found, as would every mill in Michigan, Kentucky, and Pennsylvania it modeled.

DHS was explicit that it had no reason to believe the Soo Locks would close, and no evidence of a specific threat.▸ The point of the report was narrower and, in its own words, harder to fix: "there are no plans or solutions that could mitigate the damage to the manufacturing industries dependent on this supply chain." The only structural fix identified was a second Poe-sized lock — which, in 2015, did not exist and was not funded.

Congress had actually authorized a second Poe-sized lock back in 1986, and reauthorized it twice more, but for decades it went essentially unbuilt — a text-book "authorized, not appropriated" project.▸ That changed only once real construction money started arriving after 2018. Since then, the project's own "fully funded cost" — the Army Corps' term for what the whole job will actually take, all in — has moved substantially, four times on the record:

In January 2022, Senators Gary Peters and Debbie Stabenow announced $478.9 million from the newly passed Infrastructure Investment and Jobs Act, describing it as the money that would "fully fund" the new lock — putting the total project cost, at that moment, at $1.3 billion.▸ Six months later, when the Army Corps awarded the $1.068 billion base contract for the lock's main chamber (Phase 3) to the joint venture Kokosing Alberici Traylor, the Corps' own certified fully-funded-cost estimate for the same project was $3.189 billion — more than double the number attached to the "fully funding" announcement that same year. The Corps attributed the jump to market volatility, inflation, labor shortages, and design changes.

The number then held near that level — Congress's 2022 Water Resources Development Act reauthorized the project up to roughly $3.2 billion — until September 2025, when the Corps certified a new fully-funded cost of $2.619 billion, a 13 percent, roughly $250 million cut, per Engineering News-Record's reporting on the recertification.▸ The Corps attributed the reduction to eliminated contingency, now that every remaining phase of construction had a signed contract attached to it — not to less work being done.

Two federal infrastructure-law grants cover just over a quarter of the current certified cost.▸ The rest comes the way most Army Corps construction does: appropriated year by year, in the annual Energy and Water Development bill, alongside every other civil-works project competing for the same account.

The dependence on annual appropriations is why the project's own advocates keep describing its funding as fragile even now, three-quarters of the way through construction.▸ A May 2025 Michigan Public report on that year's budget fight quoted a Michigan senator's office warning that a House Republican budget proposal would "severely restrict" funding for the project — construction that, by then, already had roughly 500 workers on site.

The lock itself is being built inside the St. Marys River, and there is no road to it.▸ Every workday, about 500 construction workers are ferried out to the job site and back — carpenters, ironworkers, laborers, and heavy-equipment operators from Carpenters Locals 202 and 1510, Ironworkers Local 8, LiUNA Local 1239, and Operating Engineers Local 324, working under Kokosing Alberici Traylor's Phase 3 contract. The new chamber will match the Poe Lock's own dimensions — 1,200 feet long, 110 feet wide, 32 feet deep — so that when it opens, the system finally has two locks, not one, able to pass the largest lake freighters.

Phase 1 (channel deepening) and Phase 2 (approach-wall rehabilitation) are complete.▸ Phase 3 — excavating and pouring the lock chamber itself — has run through a sequence of contract options awarded piece by piece: $222.7 million for Option 3 in September 2024, $95.3 million for the three remaining options in June 2025. The Army Corps says the project remains on schedule for a summer 2030 completion, by which point the Poe Lock it is meant to back up will be 62 years old.

This piece covers the New Lock at the Soo (Sault Ste. Marie, Michigan) only; it does not cover the Soo Locks' separate operations-and-maintenance budget, the 2026 shipping-season pilotage or Coast Guard icebreaking costs, or Canadian-side infrastructure on the St. Marys River.