Gulf of Mexico

The Gulf of Mexico (Spanish: Golfo de México) is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southwest and south by the Mexican states of Tamaulipas, Veracruz, Tabasco, Campeche, Yucatán, and Quintana Roo; and on the southeast by Cuba.

The Gulf of Mexico basin is roughly oval and is about 810 nautical miles (1,500 kilometres; 930 miles) wide. Its floor consists of sedimentary rocks and recent sediments. It is connected to part of the Atlantic Ocean through the Straits of Florida between the U.S. and Cuba, and with the Caribbean Sea via the Yucatán Channel between Mexico and Cuba. Because of its narrow connection to the Atlantic Ocean, the gulf has very small tidal ranges. Moisture from the Gulf of Mexico also contributes to weather across the United States, including severe weather in Tornado Alley.

The size of the gulf basin is about 1.6 million square kilometres (620,000 square miles). Almost half of the basin consists of shallow continental shelf waters. The volume of water in the basin is roughly 2.4 million cubic kilometres (580 thousand cubic miles). The gulf is one of the most important offshore petroleum production regions in the world, making up 14% of the total production for the United States.

Name

As with the name of Mexico, the gulf's name is associated with the ethnonym Mexica, which refers to the Nahuatl-speaking people of the Valley of Mexico better known as the Aztecs. In Aztec religion, the gulf was called Chalchiuhtlicueyecatl, or 'House of Chalchiuhtlicue', after the deity of the seas. Believing that the sea and sky merged beyond the horizon, they called the seas ilhuicaatl, meaning 'sky water', contrasting them with finite, landlocked bodies of water, such as lakes. The Maya civilization, which used the gulf as a major trade route, likely called the gulf nahá, meaning 'great water'.

Up to 1530, European maps depicted the gulf, though left it unlabeled. Hernán Cortés called it "Sea of the North" (Spanish: Mar del Norte) in his dispatches, while other Spanish explorers called it the "Gulf of Florida" (Golfo de Florida) or "Gulf of Cortés" (Golfo de Cortés). A 1584 map by Abraham Ortelius also labeled it as the "Sea of the North" (Mare de Nort). Other early European maps called it the "Gulf of St. Michael" (Latin: Sinus S. Michaelis), "Gulf of Yucatán" (Golfo de Iucatan), "Yucatán Sea" (Mare Iuchatanicum), "Great Antillean Gulf" (Sinus Magnus Antillarum), "Cathayan Sea" (Mare Cathaynum), or "Gulf of New Spain" (Spanish: Golfo de Nueva España). At one point, New Spain encircled the gulf, with the Spanish Main extending into what later became Mexico and the southeastern United States.

The name "Gulf of Mexico" (Spanish: golfo de México; French: golphe du Mexique, later golfe du Mexique) first appeared on a world map in 1550 and a historical account in 1552. As with other large bodies of water, Europeans named the gulf after Mexico, land of the Mexica, because mariners needed to cross the gulf to reach that destination. This name has been the most common name since the mid-17th century, when it was still considered a Spanish sea. French Jesuits used this name as early as 1672. In the 18th century, Spanish admiralty charts similarly labeled the gulf as "Mexican Cove" or "Mexican Sound" (Ensenada Mexicana or Seno Mexicano). Until the Republic of Texas broke away from Mexico in 1836, Mexico's coastal boundary extended eastward along the gulf to present-day Louisiana.

Among the other languages of Mexico, the gulf is known as Ayollohco Mexihco in Nahuatl, u golfoil México in Yucatec Maya, and golfo yu'un México in Tzotzil. Although there is no formal protocol on the general naming of international waters, Gulf of Mexico is officially recognized by the International Hydrographic Organization, which seeks to standardize the names of international maritime features for certain purposes and counts all three countries adjacent to the gulf as member states.

In a January 2025 executive order, United States president Donald Trump directed federal agencies to adopt the name "Gulf of America" for the waters bounded by the U.S. Some major online map platforms and several U.S.-based media outlets voluntarily adopted the change, but it also stoked controversy, with Mexican president Claudia Sheinbaum and others objecting to the declaration. A February 2025 poll by Marquette University found that, among 1,018 respondents across the U.S., 71% opposed renaming the Gulf of Mexico and 29% supported the name change.

Extent

The International Hydrographic Organization publication Limits of Oceans and Seas defines the southeast limit of the Gulf of Mexico as:

A line joining Cape Catoche Light (21°37′N 87°04′W) with the Light on Cape San Antonio in Cuba, through this island to the meridian of 83°W and to the Northward along this meridian to the latitude of the South point of the Dry Tortugas (24°35′N), along this parallel Eastward to Rebecca Shoal (82°35′W) thence through the shoals and Florida Keys to the mainland at the eastern end of Florida Bay and all the narrow waters between the Dry Tortugas and the mainland being considered to be within the Gulf.

Population

The Gulf Coast of the United States, or Gulf Coastal Region, is composed of parts of the five U.S. states facing the Gulf. In 2016, the total population of the region was 15.8 million people. Major cities along the coast include Houston, Texas; New Orleans, Louisiana; Mobile, Alabama; and Pensacola, Florida.

The six Mexican states that face the gulf have a total population of 19.1 million people.

Three provinces of northwest Cuba, including Havana, border on the gulf, have a combined population of 3,211,000.

Geology

The Gulf of Mexico took shape about 300 million years ago as a result of plate tectonics. The consensus among geologists is that before the late Triassic, the Gulf of Mexico did not exist. Before the late Triassic, the area consisted of dry land, which included continental crust that now underlies Yucatán, within the middle of the supercontinent Pangaea. This land lay south of a continuous mountain range that extended from north-central Mexico, through the Marathon Uplift in west Texas and the Ouachita Mountains of Oklahoma, and to Alabama where it linked directly to the Appalachian Mountains. It was created by the collision of continental plates that formed Pangaea. As interpreted by Roy Van Arsdale and Randel T. Cox, this mountain range was breached in the late Cretaceous by the formation of the Mississippi Embayment.

The rifting that created the basin was associated with zones of weakness within Pangaea, including sutures where the Laurentia, South American, and African plates collided to create it. Firstly, there was a late Triassic–early Jurassic phase of rifting during which rift valleys formed and filled with continental red beds. Secondly, the continental crust was stretched and thinned as rifting progressed through the early and middle Jurassic times. This thinning created a broad zone of transitional crust, which displays modest and uneven thinning with block faulting and a broad zone of uniformly thinned transitional crust, which is half the typical 40 km (25-mile) thickness of continental crust. At this time, rifting first created a connection to the Pacific Ocean across central Mexico and later eastwards to the Atlantic Ocean. This flooded the opening basin to create an enclosed marginal sea. The subsiding transitional crust was blanketed by the widespread deposition of Louann Salt and associated anhydrite evaporites. During the late Jurassic, continued rifting widened the basin and progressed to the point that seafloor spreading and formation of oceanic crust occurred. At this point, sufficient circulation with the Atlantic Ocean was established that the deposition of Louann Salt ceased. Seafloor spreading stopped at the end of the Jurassic, about 145–150 million years ago.

During the late Jurassic through early Cretaceous, the basin experienced a period of cooling and subsidence of the crust underlying it. The subsidence resulted from crustal stretching, cooling, and loading. Initially, the crustal stretching and cooling combination caused about 5–7 km (3.1–4.3 miles) of tectonic subsidence of the central thin transitional and oceanic crust. The basin expanded and deepened because subsidence occurred faster than sediment could fill it.