General Steel Industries, Inc. (GSI) was an American steel company founded as General Steel Castings Corporation in 1928. The company's first headquarters were in Eddystone, Pennsylvania and, prior to completing its own modern steel foundry in 1930, acquired the operations of the Commonwealth Steel Company, a critical supplier to the rail industry. In 1974, GSI was operating 19 plants across the United States and internationally and continued operating as an independent company until it was acquired by in 1981.