The Southern Coastlands

United States Geography

The southern margins of the United States can be divided into two approximately equal sections. One half, the Southwest Border Area, shares a long land boundary with Mexico and includes an extensive inland area that has experienced many influences from that country. The other half, which we discuss here, traces the coastline eastward from the mouth of the Rio Grande River in Texas to North Carolina and includes the Florida peninsula. Both stretches are southerly in latitude, and they share a small area of overlap in southern Texas, but the Southern Coastlands is as distinct from the Southwest Border Area as are any other two adjacent regions in America.

The Southern Coastlands is distinctive for two primary reasons. First, it has a humid, subtropical environment. The warm waters of the Gulf of Mexico also contribute a strong maritime influence to the coastlands' climate. The region has a clear appeal to visitors and potential residents, and its agriculture is distinctive because of this environment.

Second, the region's role in generating U.S. trade patterns with the rest of the world and its distinctive industrial pattern also help to define it.

A third factor relevant to the character of the region is its position between the Deep South and Latin America. The cultural influences on the region from Latin America were buffered for a long time by the water separating most of the Coastlands' population from their neighbors. But in recent decades, the growth of the population of Cuban heritage in southern Florida and the intensification of trade between Latin America and the United States has emphasized the distinctive character of this region.


Of the several components that make up a physical environment, climate has the greatest impact on the human geography of the Southern Coastlands. A humid subtropical climate, a long growing season, mild winter temperatures, and warm, humid summers all contribute to patterns of human activity associated with the region.

Only in southern California, southwest Arizona, and Hawaii is the average length of the growing season equivalent to that in the Southern Coastlands. Measured as the number of days between the last killing frost in the spring and the first frost in the fall, almost the entire region experiences nine months or longer of potential growth for its agricultural crops. Also, almost the entire region receives precipitation abundant enough for most agricultural activities--an average rainfall in excess of 125 centimeters, with most of the rain falling in the summer between April and October, when sunlight is plentiful and warm temperatures support plant growth.

There are two primary consequences of these climatic conditions. First, as long as other agricultural conditions are met, such as fertile soil, appropriate ground drainage, and control of insect pests, farmers can grow their crops without fear of frost until late in the fall. In a few locations, it is possible to harvest two crops in one growing season, and some vegetable farmers are achieving even more. Second, and even more important, is the opportunity for production of specialty crops that can be grown in few other locations in the United States.

Citrus production has been a particularly important contributor to Florida's economy since it was first introduced to the region by Spaniards during the 16th century, although the areas of primary production have gradually shifted southward along the peninsula's interior.

Oranges and grapefruit are the most important of the seven major citrus fruits grown in the state. In 1992 over 6 million tons of oranges were harvested. Since 1945, an increasing share of the orange crop--now at about 80 percent--has been processed rather than sold as fresh oranges. By processing the oranges (mostly into frozen concentrate), a sizable industry has developed in Florida, spreading the benefits of this specialty crop among a larger proportion of the state's population than if only fresh fruit were shipped northward. In addition, processing allows year-round sales instead of limiting returns to the immediate harvest period.

Grapefruit is produced in an area almost coincident with orange production, but total demand is lower and output is only about one-fourth that of the more important crop. Significant orange and grapefruit farming is also found under irrigation in the extreme southern portion of Texas.

Since citrus fruits are tree crops, a major share of their production costs are associated with the harvest. The fruit must be hand-picked, often from the top of a long ladder. Large amounts of short-term labor are required during the citrus harvest, which annually draws thousands of migrant laborers to dense, park-like groves for periods of intense physical effort.

Sugarcane production is exclusive to the Southern Coastlands in the mainland United States. Sugarcane is a perennial crop requiring more than one year for full maturity, and it is not tolerant of frost. In addition, water requirements for cane are high--a minimum rainfall of about 125 centimeters per year. Both temperature and water requirements would seem to preclude growth in the continental United States except under irrigation, but moderately large quantities of cane are grown in Louisiana and Florida.

Rice is less demanding than sugarcane in its climatic requirements. Given sufficient water, rice will mature within one growing season at a rate roughly in proportion to the amount of heat it receives during the summer. Within the Southern Coastlands region, irrigated rice is grown in Louisiana and Texas.

In addition to the specialty crops, portions of the Southern Coastlands are among the country's primary regions of vegetable production. Most fresh vegetables reaching the urban markets during the winter are grown in Florida and the southern margins of the other Gulf coastal states. Also, efforts to eradicate the cattle-fever ticks, upgrade pasturage, and crossbreed hardy Brahman bulls with improved domestic cattle has made the Florida beef industry an important contributor to that state's economy.

Although climatic conditions in the region are favorable for agriculture, soil conditions and quality are much more variable. The soils range from the fertile but poorly drained muck of the Louisiana coast and Mississippi Delta to extremely sandy soils in northern and central Florida. To complicate the pattern, sections of Gulf coastal Florida and the state's extensive Everglades region are largely swampy muck soils or poorly drained sands, while the coasts of Texas, Georgia, and South Carolina may have either marsh soils or sandy soils, depending on local conditions. Areas of muck in Louisiana have proven to be extremely productive, especially for sugarcane and rice, once they have been drained.

In sharp contrast, much of the remainder of the Southern Coastlands benefits from heavy irrigation. The central highlands of Florida, for example, are underlain by sandy soils with moderately poor to very poor water retention capacity. The productive citrus-growing region and vegetable areas have yielded annual output as much as 10 times more valuable when the crops are irrigated than when precipitation is relied on as the sole source of moisture. With this degree of improvement possible and the technological capacity available for its achievement, the distinctive subtropical environment of the Coastlands has been developed agriculturally beyond the levels found in much of the interior Southeast.

Recreation and retirement are also major industries for the Southern Coastlands. Even by the early 1950s, the importance of amenity factors in stimulating the regional growth of Florida and the Gulf Coast was clear; since then their effects have increased.

A direct economic advantage is also generated by tourist activities in the region. Between New Orleans, Louisiana, and Mobile, Alabama, the coastal section of Mississippi has experienced a tourist boom with construction of numerous hotels, motels, restaurants, and artificial beaches.

The most dramatic tourist magnet in the region, however, has been Florida. With long beaches facing both the Atlantic Ocean and the Gulf of Mexico, this state has drawn winter vacationers for decades. The demand for subtropical amenities has become so strong that the development of recreation resources has spread well north along the Atlantic margin into coastal Georgia and coastal South and North Carolina.

Not all tourist attractions depend on resources provided by nature. The construction of Disneyworld has brought millions of out-of-state visitors to south-central Florida. Many other new attractions were drawn to this part of the state, especially around Orlando, by the promise of tourist traffic and the possibility of tourist expenditures. This central Florida recreation complex is expected to become the inland link between Florida's east coastal and west coastal urban clusters.

Although the Southern Coastlands' subtropical environment has many advantages, this environment is not entirely beneficent. Agriculturally, successful vegetable production has encouraged growers to attempt to produce crops year-round. Thus, when an occasional midwinter frost reaches into southern Florida, considerable crop damage can occur. Similarly, Florida citrus is harvested between October and late May, and a winter freeze can hurt the ripening fruit. Less well publicized is the potential damage of these untimely wintry blasts for sugarcane growers in Louisiana.

More erratic, more sporadic, more dramatic, and locally more destructive are the region's hurricanes--large cyclonic storms generated by intense solar heating over large bodies of warm water. Because these storms are an accepted feature of the region, and weather satellites and other forecasting tools are available, preparations to withstand the greatest force of the wind and rain can be made early. And because the heaviest damage is usually limited to a relatively narrow swath as the storm moves onshore, many portions of the region have not been affected for years. On the other hand, because hurricanes are so variable in occurrence and strength, settlements have spread in spite of warnings into coastal areas that are very much exposed to the dangers of a large storm.


The coastline of the Gulf of Mexico has only a few good-quality harbors suitable for large-volume trade activities. A shallow, emergent coastline containing many high-action beaches, much of the coast itself is either backed by extensive swamps or partially shielded behind offshore bars. If passage can be made through gaps in the sand bars, protection from rough seas is gained. Coastwise shipping uses this protection in the intracoastal waterway system. However, since most bays behind the bars are too shallow to provide good anchorage for ships engaged in transoceanic trade, most of the larger ports have developed on the edge of large river estuaries along the coastline or a short distance inland from the mouths of rivers emptying into the Gulf of Mexico or the Atlantic Ocean.

Each of the bays providing good harbor facilities is the outlet for a river draining a part of the interior, but these rivers vary greatly in navigability. All assisted early settlement expansion, and some are still navigated by small barges. All have had their access to the continental interior strengthened by rail connections with major inland markets, or the river flowing into the coastal harbor has been improved for better navigation. Jacksonville, for example, was an early terminus for railroads entering Florida from Georgia. It also was the main focus for a hinterland that extended westward into the state's "Panhandle" and south into the agriculturally rich central highlands. A result was that Jacksonville was well established even before highway connections reinforced its locational bases for growth.

New Orleans is in a class by itself in terms of accessibility. It formerly was both a control point and a shipping focus for the entire Mississippi River system. The Mississippi was navigable (with caution) by shallow draft paddle-wheel steamers far to the north, well into the agricultural heartland. The river's main tributaries extended the single waterway system both westward into the Great Plains and eastward into the manufacturing core. New Orleans' site, within a large river meander and on the low-lying river delta only a few meters above mean sea level, meant that flooding was an annual threat often realized. But the city's situation was of such tremendous advantage to all associated with trade that its population grew early in the 19th century and has remained large.

New Orleans' French colonial heritage is consciously maintained in the city's French Quarter. And a distinctive mix of local Creole, Cajun, and European cuisines, a wealth of jazz and performances, and 18th-century architecture have drawn millions of tourists to the city. A visitor to New Orleans may be surprised by the heavy barge and ship traffic on the river (it is the busiest port in America) and by the heavy industry supported by this traffic.

The other major city in the western portion of the Southern Coastlands, the largest in the entire region by 1970, provides a contrast with New Orleans. Houston, Texas, is a new city in many ways. It was not originally a port city but has become one through construction (beginning in 1873) and repeated improvement of the Houston Ship Channel across shallow Galveston Bay. Its port connections became more important to growth in the late 1940s with the rise of the local petrochemical industry.

The main themes that characterize the Southern Coastlands can be found uniquely represented in the unparalleled cultural transformation of the greater Miami, Florida, region.

Through the 1950s, Miami's attractions were treated as passive characteristics of place. It was enough to enjoy what was there. The city's weather was warm throughout the winter; its coastal location provided easy access to long beaches and warm tropical waters; the harbor required only modest improvement to ease the travel of cruise passengers from America to the Caribbean islands nearby. It was not until the 1960s that the region's location at the southern extremity of the continental margin led to the full integration of Miami into a hemispheric system of finance and commerce.

Key to the change in Miami's use of its location was Cuban immigration. Between 1959 and 1981, the Latin American population of the greater Miami area (about 85 percent of which is Cuban) grew from 25,000 to almost 700,000.

The Cuban population was absorbed relatively quickly into financial, commercial, and retail activities. The rapidity with which large numbers settled in Miami created its own "instant" market. Businesses in other parts of the United States that wished to expand their activities into Latin American markets began to move at least part of their domestic operations to Miami to employ the Spanish-speaking Cubans. The trans-Caribbean business contacts brought with the Cuban refugees were also attractive to Anglo business interests. Multiplied many times in many ways and over several decades, this pattern has opened up Miami's natural geographic orientation toward the south.


The true physical margin of North America as a continent does not coincide with the seacoast. A shelf of land below sea level extends beyond the coastline. In some cases, the shelf extends only a few kilometers, but along much of the Atlantic Coast and in the Gulf of Mexico, the edge of this shelf may lie more than 80 kilometers from shore. Mineral exploration along the coast from the Rio Grande River to the mouth of the Mississippi River has led to the discovery of an extensive series of petroleum and natural gas deposits, both onshore and off.

When the Gulf Coast oil field was brought into production during the early 1900s, Houston was still a moderate-size city of less than 75,000. When the 1990 census was taken, the city had grown to 1.6 million, to rank it fourth in the United States behind New York, Los Angeles, and Chicago. Located about midway along the long coastal arc between the Mississippi River and the Mexican border, Houston also lies at the coastal apex of the Texas Triangle joining the cities of Dallas-Fort Worth and San Antonio. With Dallas ranked eighth in population in 1990 and San Antonio ranked tenth, connections with these major inland growth centers and the large cotton exports that originate in eastern Texas have also contributed to the locational strength of Houston.

The search for additional petroleum deposits along the Gulf Coast was extended seaward before mid-century. The petroleum companies' success created new problems, even while economic problems were temporarily alleviated by the discoveries. In overcoming the technological difficulties of drilling for and extracting petroleum using platforms far beyond sight of land, conflicting claims between state and federal governments over jurisdiction of continental shelf resources flared. One result of a complex series of court cases has been variable jurisdiction: Florida and Texas are sanctioned to claim up to 15.3 kilometers seaward, while Louisiana, Alabama, and Mississippi are limited to 4.8 kilometers.

The continuous rapid increase in domestic consumption of petroleum, natural gas, and petroleum products led the federal government, during the early 1970s, to open commercial bidding on offshore tracts between Biloxi, Mississippi, and Tampa Bay, Florida, and, beginning in the early 1980s, off the Atlantic Coast.

So extensive are the petroleum deposits along the coast between northern Mexico and the Mississippi River that the resource importance of the Southern Coastlands would be a national priority even if these deposits were the region's only mineral resource. Texas and Louisiana are currently two of the three leading petroleum-producing states (with Alaska). And while Texas and Louisiana possess large producing fields well inland from the Gulf, the coastal fields are major contributors to both states' totals.

The numerous scattered Gulf Coast deposits of natural gas are spatially intermingled with the region's long arc of petroleum deposits. Pipelines to carry the gas radiate from the main coastal production centers to the primary consumption points across the country and within the Manufacturing Core.

Also, geologic formations of the Texas and Louisiana coastlands that contain petroleum and natural gas contain two additional minerals of economic value--sulfur and rock salt. The subsurface rock contortions found where petroleum and natural gas have been trapped in economically recoverable deposits were formed in this region by the gradual upthrust of large salt domes. Far less valuable than either of the mineral fuels, rock salt is nonetheless mined in large quantities in southwestern Louisiana. More valuable than salt is the sulfur found in the caprock covering many of the salt domes. The large sulfur deposits at Beaumont, Texas, and across the state boundary near Lake Charles, Louisiana, supply all U.S. needs. Additional deposits both inland and beneath the continental shelf indicate an abundance of this mineral for many years. Also of national significance is phosphate production from substantial deposits in Florida.

Petroleum and natural gas extraction do not, by themselves, usually generate strong local urban and industrial growth. The process of exploration and drilling requires specialized and expensive equipment but not the large variety of support materials or labor demanded by many mining operations. However, large-volume petroleum production can generate tremendous quantities of capital in a short time, and locally accumulated wealth has attracted a variety of industries able to use the minerals near their production sites. Petroleum refineries were built outside all major ports from Corpus Christi, Texas, to Pascagoula, Mississippi, with the most intensive concentration around Houston, Beaumont, and Port Arthur in Texas.

Of broader development impact are the industries that depend on the refinery output for their own existence, such as petrochemicals. Natural gas and petroleum products are used as chemical components for a great many products. Items ranging from plastics, paints, and antifreeze to fertilizer, insecticide, and prescription drugs have their origin in chemical plants located along the western Gulf Coast. In addition, other chemical industries not tied to petroleum and natural gas production, such as those producing sulfuric acid, superphosphate fertilizer, and synthetic rubber, are major consumers of sulfur and salt. The coincidence of the basic minerals within a region possessing large capital investment capabilities has supported rapid economic and population growth.

There is also more to the location of industry, however, than the availability of capital and proximity to raw materials, even petrochemical industries--there is the matter of accessibility. The Southern Coastlands, as noted, is on the continental margin and as such constitutes the line of exchange between water transport and land transport. Further, since water transportation is cheaper than land transport, shipment of the finished products from the Gulf Coast can be accomplished efficiently by ocean carrier to the ports of Megalopolis and by barge via the intracoastal waterway and the Mississippi River system to the manufacturing core. Conversely, products and raw materials can be moved more efficiently to Gulf Coast industries.

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Source: U.S. Department of State