The oil and gas industry comprises a very important part in the history and economy of coastal states in the Gulf of Mexico (GOM) region. In Louisiana in particular, where the impact of the oil and gas industry is the greatest, the history of oil and natural gas extraction dates back to the turn of the present century. After the discovery of the Heywood well six miles from Jennings in 1901, oil wells have been drilled in many parts of Louisiana, including Caddo, Webster, Claiborne and Union parishes in the north, La Salle parish in the central part of the state, and in most coastal parishes in the south and in the GOM off the Louisiana coast. The Exxon refinery in Baton Rouge, which is the largest oil refinery in the United States, went on-stream in 1909.