U.S. Steel has approved full funding for a nearly $3 billion Mon Valley hot strip mill at its Edgar Thomson Plant in Braddock, Pa., near Pittsburgh. The company announced the board decision Oct. 22 and said the new mill will increase annual production capacity “from approximately 2.2 million tons to approximately 3.5 million tons” and expand the range of steels it can make for customers, according to its release.
Construction will begin after the necessary permits are received, with initial production expected in late 2029, U.S. Steel said.
What a Hot Strip Mill Does
A hot strip mill is the step that turns steel slabs into coil. “A hot strip mill transforms steel slabs into thin coils used to manufacture products including vehicles, appliances and construction materials,” U.S. Steel said in its release. The new mill will heat the slabs before pressing them into long, thin coils, The Allegheny Front reported.
It will use walking beam furnaces and an in-line slab sizing press. U.S. Steel says that equipment will use less fuel, eliminate a cutting step and reduce scrap. The Allegheny County Health Department’s draft air quality permit, dated Sept. 30, 2026, lists two walking beam furnaces rated at 300 tons per hour each and a hot strip mill with a capacity of 3,500,000 tons per year.
The furnaces will burn natural gas and coke oven gas captured from the company’s coke plant in nearby Clairton, the outlet reported.
What the Mon Valley Hot Strip Mill Replaces
The Mon Valley hot strip mill would replace an aging operation at U.S. Steel’s Irvin Plant in West Mifflin, according to The Allegheny Front. Today, the company makes slabs at Edgar Thomson and ships them by rail to Irvin, where they are reheated and rolled into coils. Building the mill at Edgar Thomson will save the company from having to transport the slabs by rail, the outlet reported.
The county’s draft permit says that after “a reasonable shakedown period when the new HSM is at full operation,” U.S. Steel will shut down the five reheat furnaces at the Irvin Plant. Edgar Thomson, which The Allegheny Front notes opened in 1875, would then handle the work from slab to coil on one site.
Separate from the mill, U.S. Steel said construction is underway on an approximately $100 million slag granulator at Edgar Thomson. The company says it will turn blast furnace slag into material that can be used in cement and construction.
Jobs and Economic Impact in Pennsylvania
An economic impact study cited in U.S. Steel’s release estimates the project will support between 5,100 and 6,300 jobs across Pennsylvania and generate between $46 million and $58 million in state and local tax revenue over three years. The company said those jobs would be in addition to the 13,687 jobs it currently supports in the state, and it put the project’s economic impact at up to $1.7 billion over three years.
“For generations, the Mon Valley has built America, and steel has built lives here,” said David Burritt, President and CEO of U.S. Steel. “We are building the future of steel right here in the Mon Valley.”
Sen. Dave McCormick (R-Pa.) said in the release, “This is exactly what we fought for: real investment, good-paying jobs, and a strong future for American steelmaking in the Mon Valley.” He added, “Thanks to President Trump’s leadership, we secured a historic agreement, and now we’re seeing that commitment turn into action.”
Gov. Josh Shapiro said the investment “will keep thousands of jobs here in our Commonwealth and create real opportunity for future generations of Pennsylvania steelworkers.”
Owned by Nippon Steel, Headquartered in Pittsburgh
U.S. Steel has been owned by Tokyo-based Nippon Steel since the two companies completed their deal on June 18, 2025. As part of that deal, the companies entered into a National Security Agreement with the U.S. government, and committed that U.S. Steel will remain a U.S.-incorporated company headquartered in Pittsburgh. U.S. Steel’s announcement of the Mon Valley mill does not say how the project relates to the investment commitments in that agreement.
What It Means for Steel Buyers
U.S. Steel named three markets for the new mill’s steel. “This investment gives us the chance to produce steel for products that will be in demand for decades to come and compete across the automotive, appliance and line pipe markets like never before,” said Scott Buckiso, the company’s executive vice president and chief manufacturing officer.
Jiji Press reported that U.S. Steel aims to expand output of automotive steel sheets and other products at the new mill. For U.S. Steel hot strip mill customers, the dates to watch are the county permit decision and the late-2029 target for initial production.
Permits Still Pending
The project still needs its county air quality permit. The Allegheny Front reported that the mill will lower U.S. Steel’s overall pollution in Allegheny County but would increase the Edgar Thomson Plant’s emissions of fine particles by more than 40 percent. Health department officials said their modeling showed the project would not cause the county to exceed federal air pollution limits, according to the outlet.
The Allegheny County Health Department will hold a public hearing on the permit Nov. 10 in Braddock and accept written comments through 11:59 p.m. Nov. 17, according to the department’s public notice.
For other American producers, see the Manufacturers Lists steel manufacturers list.
Comments