High Quality Content by WIKIPEDIA articles! The United States Steel Corporation (NYSE: X), more commonly known as U.S. Steel, is an integrated steel producer with major production operations in the United States, Canada, and Central Europe. The company is the world`s tenth largest steel producer ranked by sales (see list of steel producers). It was renamed USX Corporation in 1991 and back to United States Steel Corporation in 2001 when the shareholders of USX spun off its steel-making assets following the acquisition of Marathon Oil in 1982. It is still the largest domestically owned integrated steel producer in the United States, although it produces only slightly more steel than it did in 1902.