The Gulf of Mexico () 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 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. The Gulf of Mexico has relatively narrow connections to the Atlantic Ocean, which causes only very small tidal ranges to occur. 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 . Almost half of the basin consists of shallow continental shelf waters. The volume of water in the basin is roughly (). The gulf is one of the largest offshore petroleum production regions in the world, making up 14% of the total production of crude oil 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 , or "house of Chalchiuhtlicue", after the deity of the seas. Believing that the sea and sky merged beyond the horizon, they called the seas , 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 , meaning "great water".
Up to 1530, European maps depicted the gulf, though left it unlabeled. Hernán Cortés called it "Sea of the North" () in his dispatches, while other Spanish explorers called it the "Gulf of Florida" () or "Gulf of Cortés" (). A 1584 map by Abraham Ortelius also labeled it as the "Sea of the North" (). Other early European maps called it the "Gulf of St. Michael" (), "Gulf of Yucatán" (), "Yucatán Sea" (), "Great Antillean Gulf" (), "Cathayan Sea" (), or "Gulf of New Spain" (). 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" (; , later ) first appeared on a world map in 1550 and in 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" ( or ). 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 in Nahuatl, in Yucatec Maya, and 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, U.S. president Donald Trump directed federal agencies and the U.S. Board on Geographic Names (BGN) to rename that part of the gulf lying in U.S. territorial waters as the "". Some major online map services and several U.S.-based conservative media outlets voluntarily adopted the change for their U.S. users, but otherwise its reach has been limited. It did stoke 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 () 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 bordering the Gulf. In 2016, the total population of the region was 15.8 million people.
The six Mexican states that border the Gulf have a total population of 19.1 million people."Censo de Población y Vivienda 2020 – SCITEL" (in Spanish). Retrieved January 26, 2025.
The three westernmost provinces of Cuba, including Havana, border the Gulf and have a combined population of 3,211,000.
Historically, there has also been significant human habitation within the gulf due to industrial activity. By 1975, 400 offshore drilling rigs in the gulf hosted a temporary population of more than 10,000 workers on any given day, who were rotated on a weekly staggered schedule. Increasing automation later led to a decline in the offshore worker population.
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 Arkansas and 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 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 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.
Later, loading of the crust within the basin and adjacent coastal plain by the accumulation of kilometers of sediments during the rest of the Mesozoic and all of the Cenozoic further depressed the underlying crust to its current position about below sea level. Particularly during the Cenozoic, a time of relative stability for the coastal zones, thick clastic wedges built out the continental shelf along the northwestern and northern margins of the basin.
To the east, the stable Florida Platform was not covered by the sea until the latest Jurassic or the beginning of Cretaceous time. The Yucatán Platform was emergent until the mid-Cretaceous. After both platforms were submerged, the formation of carbonates and evaporites has delineated the geologic history of these two stable areas. Most of the basin was rimmed during the early Cretaceous by carbonate platforms, and its western flank was involved during the latest Cretaceous and early Paleogene periods in a compressive deformation episode, the Laramide Orogeny, which created the Sierra Madre Oriental of eastern Mexico.
The Gulf of Mexico is 41% continental slope, 32% continental shelf, and 24% abyssal plain, with the greatest depth of 12,467 feet in the Sigsbee Deep.
Seven main areas are given as: Gulf of Mexico basin; contains the Sigsbee Deep. Northeast Gulf of Mexico; extends from a point east of the Mississippi River Delta near Biloxi to the eastern side of Apalachee Bay. South Florida Continental Shelf and Slope; extends along the coast from Apalachee Bay to the Straits of Florida and includes the Florida Keys and Dry Tortugas. Campeche Bank; extends from the Yucatán Straits in the east to the Tabasco–Campeche Basin in the west and includes Arrecife Alacran. Bay of Campeche; a bight extending from the western edge of Campeche Bank to the offshore regions east of Veracruz. Western Gulf of Mexico; located between Veracruz to the south and the Rio Grande to the north. Northwest Gulf of Mexico; extends from Alabama to the Rio Grande.
Brine pools A number of brine pools, sometimes called brine lakes, are known on the seafloor of the northern half of the Gulf of Mexico. Brine pools in the Gulf of Mexico range from just across to long. Brine is produced wherever the water of the Gulf comes in contact with the Louann Salt, an evaporite formation from the Jurassic period, along faults or in unconsolidated sediments. The Louann Salt extends under most of the continental shelf around the northern part of the Gulf from west of Florida to Texas. Under the pressure of overlaying sediments, the salt deforms and migrates, a process known as salt tectonics. Masses of salt may rise through overlaying sediments to form salt domes, or may be extruded along the Sigsbee Escarpment where the slope of the continental shelf exposes lower laying stata.