United States Gypsum Company, a subsidiary of USG Corporation, serves customers in the United States, Canada and Mexico. The company is one of the largest manufacturers and marketers of gypsum-based products in North America. Incorporated in 1901, it has a work force of more than 4,800 employees and sales revenue of over $1 billion. United States Gypsum Company provides wallboard, cement board and joint compounds. It markets its products under the SHEETROCK, FIBEROCK, SECUROCK and DUROCK brand names. In addition, the company owns and operates a fleet of oceangoing cargo ships based in Bermuda. United States Gypsum Company s products are used as dietary calcium additives and soil nutrients and conditioners.