U.S. Steel’s board of directors has approved full funding for a nearly $3 billion investment in a new hot strip mill at the company’s Mon Valley Works – Edgar Thomson Plant in Braddock, Pennsylvania, just outside Pittsburgh.
The project will replace aging equipment with updated steelmaking technology, raising the plant’s annual production capacity from roughly 2.2 million tons to about 3.5 million tons. It will also let U.S. Steel produce a wider range of steel products for customers.
Construction is set to begin once the company secures the necessary permits, with initial production targeted for late 2029. U.S. Steel says it is continuing to work with regulators through the permitting process and plans to keep the surrounding community informed as the project advances.
The Braddock investment is one piece of a much larger spending plan by Nippon Steel, the Japan-based company that acquired U.S. Steel for $14.9 billion last year. Nippon Steel has committed to spending roughly $11 billion on U.S. operations by the end of 2028, covering equipment upgrades and facility expansions across several sites.
The Mon Valley hot strip mill project has grown substantially since it was first proposed. Nippon Steel initially disclosed plans in August 2024 to upgrade or replace the mill for at least $1 billion, a condition tied to its pending acquisition of U.S. Steel at the time. The company more than doubled that commitment in June of this year. During a more recent earnings presentation, Nippon Steel told investors it intended to finalize approval of the project no later than March 2027 — a timeline the board has now beaten.
The investment represents one of the more significant industrial commitments to the Pittsburgh region’s steel sector in recent years, with implications for employment and manufacturing capacity at a plant that has operated in Braddock for generations.
