The Mon Valley Works–Irvin Plant is a steel processing plant operated by

U.S. Steel The United States Steel Corporation is an American steel company based in Pittsburgh, Pennsylvania. It maintains production facilities at several additional locations in the U.S. and Central Europe. The company produces and sells steel products, ...

and historically a "hot strip mill" (sometimes referred to as a "

steel mill A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also be a plant where steel semi-fini ...

") in the

Pittsburgh Pittsburgh ( ) is a city in Allegheny County, Pennsylvania, United States, and its county seat. It is the List of municipalities in Pennsylvania#Municipalities, second-most populous city in Pennsylvania (after Philadelphia) and the List of Un ...

suburb of

West Mifflin, Pennsylvania West Mifflin is a borough in Allegheny County, Pennsylvania, United States, located southeast of downtown Pittsburgh. The population was 19,589 at the 2020 census. It is named after Thomas Mifflin, 1st Governor of Pennsylvania, signer of the U ...

. The site consists of 650 acres on a hilltop 250 feet above the Monongahela Valley. The plant has an annual capacity of 2.9 million net tons of steel from an 80″ hot strip mill, 64″ and 84″ Pickle lines, 84″ five-stand cold reduction mill, continuous annealing line, batch and open-coil annealing facilities, 84″ temper mill, 52″ hot-dip galvanizing line and a 48″ hot-dip galvanizing line, as well as the #11 Shear Line and #17 Recoil line. The #11 shear line starts with the Kline conveyor.

History

The mill was announced on May 22, 1937 and opened in phases starting on March 2, 1938 while being dedicated on December 15, 1938 for U.S. Steel and was constructed by Mesta Machinery. U.S. Steel has claimed that construction of the hilltop site required more cubic yards of earth moved (4.4 million cubic yards) than any project other than the

Panama Canal The Panama Canal () is an artificial waterway in Panama that connects the Caribbean Sea with the Pacific Ocean. It cuts across the narrowest point of the Isthmus of Panama, and is a Channel (geography), conduit for maritime trade between th ...

. The cost of the construction of the facility was estimated at $63 million ($ today). It produced its 80 millionth ton of steel in 1981 with a workforce of 4,000 that year. In 1943 a Pittsburgh grand jury indicted four Carnegie Illinois foremen for destroying records of steel plating tests conducted at Irvin. Texas Governor

Rick Perry James Richard Perry (born March 4, 1950) is an American politician who served as the 14th United States secretary of energy from 2017 to 2019 in the first administration of Donald Trump. He previously served as the 47th governor of Texas fr ...

made a major televised campaign stop at the plant in October 2011. In January 2012 a large explosion and fire rocked the plant. President

Barack Obama Barack Hussein Obama II (born August 4, 1961) is an American politician who was the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, he was the first African American president in American history. O ...

visited the plant in January 2014 to launch his program on new retirement accounts, signing the

myRA Myra (; , ''Mýra'') was a city in Lycia. The city was probably founded by Lycians on the river Myros (; Turkish: ''Demre Çay''), in the fertile alluvial plain between, the Massikytos range (Turkish: ''Alaca Dağ'') and the Aegean Sea. By the ...

at a televised ceremony at the plant. In May 2019 U.S. Steel announced a project to spend $1 billion dollars to build a combined casting and rolling facility. The project was repurposed in 2021. President

Donald Trump Donald John Trump (born June 14, 1946) is an American politician, media personality, and businessman who is the 47th president of the United States. A member of the Republican Party (United States), Republican Party, he served as the 45 ...

visited the plant in May 2025 to celebrate the newly announced partnership between U.S. Steel and

Nippon Steel (previously known as Nippon Steel & Sumitomo Metal until 2019) is Japan's largest steelmaker, headquartered in Marunouchi, Chiyoda, Tokyo. The company has four business segments, which are steelmaking, engineering, chemicals, and systems solu ...

References

External links

Official website by US SteelAerial image of the plant in 1952
{{DEFAULTSORT:Mon Valley Works-Irvin Plant Buildings and structures in Allegheny County, Pennsylvania Ironworks and steel mills in Pennsylvania History of Pittsburgh Industrial buildings and structures in Pennsylvania Industrial buildings completed in 1938 U.S. Steel 1938 establishments in Pennsylvania