Gulf of Mexico numerous bays and smaller inlets. A number of rivers empty into the gulf, most notably the Mississippi River and Rio Grande in the northern gulf, and the Grijalva and Usumacinta rivers in the southern gulf. The land that forms the gulf's coast, including many long, narrow barrier islands, is almost uniformly low-lying and is characterized by marshes and swamps as well as stretches of sandy beach. The Gulf of Mexico is an excellent example of a passive margin. The continental shelf is quite wide at most points along the coast, most notably at the Florida and Yucatán Peninsulas. The shelf
Offshore oil and gas in the Gulf of Mexico (United States) 1938, but the first oil discovery was not made until 1941, off of Jefferson County. Through 2007, Texas state waters have produced of oil and . In 2007, Texas state waters produced of oil and condensate and gas. The first oil test in offshore Alabama was made in Mobile Bay in 1951. The first discovery in state waters of offshore Alabama was made in 1979. By 2005 a total of 80 wells have been drilled in state water, and production in Alabama state water provided per year, half the state's gas production. The eastern Gulf of Mexico, which includes offshore