Commonwealth Oil Refining Company

Commonwealth Oil Refining Company, Inc. (CORCO) was an oil refinery established in the towns of Peñuelas and Guayanilla in Puerto Rico in the second half of the 20th century. At one point, the company was ranked among the 500 largest in the United States by Fortune Magazine. In 1978, it supplied 80% of all petroleum products consumed in Puerto Rico and, at 2700 employees, it was Puerto Rico's largest employer. In addition, it was considered "among the largest independent petroleum refiners and petrochemical producers in the world."