[6] The company began construction on its new foundry and headquarters on 112 acres (45 ha),[7] in Eddystone, Pennsylvania, near Baldwin Locomotive's facilities.

By 1930 the company was making one-piece locomotive beds with integral cylinders and cradle, pilot beams, Delta trailer trucks, and water-bottom tenderframes that were over 87 feet (26.52 m) long.

[11] The company, initially using the products developed by Commonwealth Steel, specialized in large castings including tank armor and gun turrets,[12] locomotive frames and trucks.

[1] After the war, the company returned to manufacturing locomotive castings in Granite City and earth-moving equipment in Eddystone.

For example, in 1961, the Eddystone plant provided 85% of the steel castings used in the Union Electric Company's new Taum Sauk hydroelectric power station near St. Louis, and produced railroad specialty products such as "the world's highest capacity flat car", weighing almost 75 tons, with a load limit of 300 tons.

[25] At the Granite City plant, General Steel x-rayed uranium ingots for the Atomic Energy Commission from 1958[26] through 1966 using two U.S.

"[29] As a defense contractor, the company manufactured cast armor hulls and turrets for the U.S. Army M-60 medium tanks, produced at Granite City and Eddystone, as part of an $8 million contract awarded by Chrysler Corporation in 1961.

Main Office: Granite City, Illinois(from 1948)[1] Housed the company's Manufacturing Research Laboratory (completed in 1960);[30] Operations consolidated at the Granite City plant in 1964[1] Granite City, Illinois (former Commonwealth plant) - In 1960, produced engineered cast steel specialty products for rail industry including one-piece cast steel flat car underframes, cast armor, and manganese wear-resistant steel castings used in mining and crushing equipment and powers shovels;[24] In 1970, produced "massive, high-strength pressure castings for steam turbine electric power generating plants, both conventional and nuclear fueled," produced cast steel products for railroads, including trucks for diesel locomotives and rapid transit and commuter cars, and wear-resistant castings for earth-moving equipment;[3] Plant grew to 127 acres (0.51 km2) with 42 acres (170,000 m2) under roof;[1] Division discontinuance announced December 14, 1972[31] Orders from the New York Transit Authority total over 1,800 subway cars;[33] Company acquired on June 30, 1960 and merged into the parent company to become a division on January 1, 1962;[21] Supplied the superstructures for the first group of 183 Vert-A-Pac automobile carriers in 1970[34] Division discontinuance announced December 14, 1972[31] and all production ended in 1973[35] In 1974 was the company's largest division[38] after the closure of the St. Louis Car division in 1973.

"The smooth, comfortable ride of the modern railroad passenger car is the direct result of General Steel's historic development of new designs of trucks with cast steel frames and bolsters"[16] but the development of new designs would at least partially result in the end of St. Louis Car.

[41] As the company's largest division at the time,[42] losses at St. Louis Car sank the entire enterprise's net income into the red.

"[43] The Castings Division had not produced satisfactory earnings for five years, lost about $3 million in 1972, and "was not competitive in most of its major markets and there were no prospects for future improvement of its position.

The five remaining operating units were: National Roll, Flex-O-Lite, Ludlow-Saylor Wire Cloth Division, Standard Pipeprotection, and Simplicity Engineering Company (a subsidiary).

General Steel continued operations at the Granite City plant until orders, pending at the time of the December 1972 announcement of the Castings Division's closing, were completed.

[47] By October 2009, most of the buildings at the former General Steel plant, including the old Commonwealth foundry at 1417 State Street, Granite City, Illinois had been demolished.