RIO GRANDE

Spanish Ro Grande del Norte, or (in Mexico) Ro Bravo, or Ro Bravo del Norte one of the longest rivers of North America, flowing some 1,900 miles (3,060 km) from its sources in the southern Rocky Mountains of southwestern Colorado to the Gulf of Mexico and marking the entire border between Texas (U.S.) and Mexico. The Rio Grande rises as a clear, snow-fed stream more than 12,000 feet (3,700 m) above sea level in the San Juan Mountains of Colorado and flows generally southward across Colorado and New Mexico. For the lower two-thirds of its course, the Rio Grande flows southeastward between Texas and the Mexican states of Chihuahua, Coahuila, Nuevo Lon, and Tamaulipas to eventually empty into the Gulf of Mexico. Its early course flows through forests of spruce, fir, and aspen into the broad San Luis valley in Colorado, after which it cuts the Rio Grande Gorge and White Rock Canyon of northern New Mexico and enters the open terrain of the Basin and Range and the Mexican Plateau physiographic provinces. Shortly before entering the Gulf coastal plain, the Rio Grande cuts three canyons between 1,500 and 1,700 feet (457 and 518 m) in depth across the faulted area occupied by the big bend region along the Texas-Mexico border. Along the remainder of its course, the river wanders sluggishly across the coastal plain to its delta on the Gulf of Mexico. The principal tributaries of the Rio Grande are the Pecos, Devils, Chama, and Puerco rivers in the United States and the Conchos, Salado, and San Juan in Mexico. The basin of the Rio Grande drains an area of about 336,000 square miles (870,000 square km), although only about half of this area contributes to the river's flow. The river's peak flow occurs from about April to October. Roughly one-third of the Rio Grande's water reached the Gulf of Mexico before the building of the Falcon Dam (1953) upstream from Rio Grande City; the river's average discharge rate is now about 3,000 cubic feet (85 cubic m) per second. The earliest European settlements were in the Conchos basin of Chihuahua in the 16th century, but many of the Pueblo Indian settlements of New Mexico date from before the Spanish conquest. During the Spanish period the river's middle and upper portions commonly were termed the Ro del Norte, or Ro Grande del Norte, and the lower course usually was called the Ro Bravo (apparently because of the turbulent flash floods). More than 2,000,000 acres (800,000 hectares) of farmland are irrigated along the Rio Grande, with slightly more than half in Mexico. The leading crops raised by irrigation vary from potatoes and alfalfa in Colorado to cotton, citrus fruits, and vegetables along the lower Rio Grande. After agriculture and animal husbandry, the region's main industries are mining and recreation. The Rio Grande basin and its drainage network. Spanish Ro Grande del Norte, or (in Mexico) Ro Bravo, or Ro Bravo del Norte, fifth longest river of North America, and the 20th longest in the world, forming the border between the U.S. state of Texas and Mexico. Rising as a clear, snow-fed mountain stream more than 12,000 feet (3,700 metres) above sea level in the Rocky Mountains, the Rio Grande descends across steppes and deserts, watering rich agricultural regions as it flows on its way to the Gulf of Mexico. The total length of the river is about 1,900 miles (3,060 kilometres). The area within the entire watershed of the Rio Grande is some 336,000 square miles (870,000 square kilometres). Because a large proportion of the river's basin is arid or semiarid, however, only about half of the total area, or about 176,000 square miles, actually contributes to the river's flow. port city, southeastern Rio Grande do Sul estado (state), southern Brazil. The city lies along the Rio Grande (river), which is the outlet to the Atlantic of the Patos Lagoon. It is built on a low peninsula, barely 5 feet (1.5 m) above sea level and 8 miles (13 km) from the river's mouth. Where it enters the ocean, the river passes over a submerged bar that has been dredged so that oceangoing vessels can dock at Rio Grande or at Pelotas, 25 miles (40 km) northwest. In 1737 a Portuguese fort called Estreito was built nearby. In 1745 its garrison and settlement were moved to the present site, which became a town in 1751 with the name of So Pedro do Rio Grande do Sul; it received city status in 1835. It was the capital of a Brazilian captaincy until 1763, when it was temporarily occupied by Spanish forces from Buenos Aires. Rio Grande competes with Pelotas as the outlet for the products of Rio Grande do Sul state. The port's exports, mostly to other parts of Brazil, include xarque (jerked beef), hides, lard, wool, rice, wheat, feijo (beans), tobacco, and frozen fish and shrimp. In the city are meat-processing plants and vegetable canneries; wool, cotton, and jute textile mills; an oil terminal and a petroleum refinery; and other factories. Rio Grande is linked to Pelotas by railway and highway, and it has an airport. Pop. (1991 prelim.) 157,608. Additional reading Flow of the Rio Grande and Related Data from Elephant Butte Dam, New Mexico, to the Gulf of Mexico (annual), published by the International Boundary and Water Commission (United States and Mexico), is an excellent source of information on the hydrology, climatology, drainage basins, and irrigated areas of the Rio Grande region. University of Texas at El Paso, Civil Engineering Department, Water Resources of the Upper Rio Grande Basin, 2 vol. (1970), contains detailed climatic, hydrologic, and reservoir data and includes information on irrigation and political and legal aspects. A wide variety of articles from numerous disciplines pertaining to the Rio Grande are found in the Natural Resources Journal (quarterly); and Journal of Borderlands Studies (semiannual). Jerry E. Mueller, Restless River: International Law and the Behavior of the Rio Grande (1975), is an informative blend of geomorphology and political geography. John W. House, Frontier on the Rio Grande (1982), focuses on the river as an international boundary and emphasizes regional political and social aspects. San Diego State University, Institute of Public and Urban Affairs, Environmental Problems Along the Border (1979), contains several pertinent articles concerning the Rio Grande. Historical works on the river include Paul Horgan, Great River: The Rio Grande in North American History (1954, reprinted 1991); Laura Gilpin, The Rio Grande, River of Destiny (1949); and Norris Hundley, Dividing the Waters: A Century of Controversy Between the United States and Mexico (1966). Robert H. Schmidt, Jr.