river blindness or onchocerciasis, disease caused by the parasitic nematode worm Onchocerca volvulus. The worm larvae are transmitted by the bites of blackflies (genus Simulium) that live in fast moving streams. Inside the body the worms form disfiguring skin nodules, where they mate. Their tiny larvae, or microfilariae, migrate through the skin, causing severe itching. If the infection reaches the area of the eye, allergic reaction to the microfilariae can cause blindness.

Tests can now detect infestation before the disease has progressed, and the new drugs ivermectin, which kills the larvae, and amocarzine, which kills adult forms, have begun to help control the disease. Blackfly eradication programs have had limited success because the flies can quickly develop resistance to pesticides.

River blindness, which occurs primarily in Africa, Central and South America, and Yemen, affects an estimated 18 million people. In Africa, two strains have been identified, a savanna strain and a forest strain. The forest strain does not usually lead to blindness, but it does cause severe skin symptoms (lesions, itching, discoloration, change in texture) that can result in social ostracism.

river, stream of water larger than a brook or creek. Land surfaces are never perfectly flat, and as a result the runoff after precipitation tends to flow downward by the shortest and steepest course in depressions formed by the intersection of slopes. Runoffs of sufficient volume and velocity join to form a stream that, by the erosion of underlying earth and rock, deepens its bed; it becomes perennial when it cuts deeply enough to be fed by groundwater or when it has as its source an unlimited water reservoir, for example, the St. Lawrence flowing from the Great Lakes.

The lowest level to which a river can erode its bed is called base level. Sea level is the ultimate base level, but the floor of a lake or basin into which a river flows may become a local and temporary base level. Cliffs or escarpments and differences in the resistance of rocks create irregularities in the bed of a river and can thus cause rapids and waterfalls. A river tends to eliminate irregularities and to form a smooth gradient from its source to its base level. As it approaches base level, downward cutting is replaced by lateral cutting, and the river widens its bed and valley and develops a sinuous course that forms exaggerated loops and bends called meanders. A river may open up a new channel across the arc of a meander, thereby cutting off the arc and creating an oxbow lake.

Rivers modify topography by deposition as well as by erosion. River velocity determines quantity and size of rock fragments and sediment carried by the river. When the velocity is checked by changes of flow or of gradient, by meeting the water mass of lakes or oceans, or by the spreading of water when a stream overflows its banks, part of the load carried by the stream is deposited in the riverbed or beyond the channel. Landforms produced by deposition include the delta, the floodplain, the channel bar, and the alluvial fan and cone.

The discharge, or rate of outflow, of a river depends on the width of its channel and on its velocity. Velocity is governed by the volume of water, the slope of the bed, and the shape of the channel (which determines the amount of frictional resistance). River volume is affected by duration and rate of precipitation in the drainage basin of the river. A river system may be enlarged by piracy, or the process by which one river, cutting through the divide that separates its drainage basin from that of another river, diverts the waters of the other into its own channel.

Traditionally river systems have been classified according to their stage of development as young, mature, or old. The young river is marked by a steepsided valley, steep gradients, and irregularities in the bed; the mature river by a valley with a wide floor and flaring sides, by advanced headward erosion by tributaries, and by a more smoothly graded bed; and the old river by a course graded to base level and running through a peneplain, or broad flat area. The age classification of rivers is diminishing in popularity now that quantitative studies of river behavior are more common.

See also flood; water rights; waters, territorial.

Important River Systems

River valleys have been important centers of civilization; they afford travel routes, and their alluvial soils form good agricultural lands. Navigable rivers are important in commerce and have influenced the location of cities. Rivers with sufficient velocity and gradient can be used to produce hydroelectric power. Among the most important river systems of the world are the Nile, the Congo, the Niger, the Zambezi, and the Orange-Vaal in Africa; the Amazon, the Orinoco, and the Paraguay-Paraná in South America; the Mississippi-Missouri, the St. Lawrence, the Rio Grande, the Colorado, the Columbia, the Mackenzie-Peace, and the Yukon in North America; the Danube, the Rhine, the Rhône, the Seine, the Po, the Tagus, the Thames, the Loire, the Elbe, the Oder, the Don, the Volga, and the Dnieper in Europe; the Tigris, the Euphrates, the Ob-Irtysh, the Yenisei, the Lena, the Syr Darya, the Amu Darya, the Amur, the Huang He, the Chang (Yangtze), the Ganges, the Brahmaputra, the Indus, the Ayeyarwady, and the Mekong in Asia; and the Murray-Darling in Australia.

Yellow River, China: see Huang He.

Wood River, city (1990 pop. 11,490), Madison co., SW Ill., on the Mississippi River just above its junction with the Missouri; inc. 1923. It has oil refineries and pipeline terminals, and petroleum additives are produced.

Wind River Range, part of the Rocky Mts., W Wyo., running southeastward c.120 mi (190 km) and constituting part of the Continental Divide. Gannett Peak (13,804 ft/4,207 m) is the highest point in Wyoming. A number of historic passes cross these mountains. South Pass (alt. c.7,550 ft/2,301 m), at the southern end of the range, was the most important pass on the Oregon Trail through the Rocky Mts.

White River. 1 River, c.690 mi (1,110 km) long, rising in the Boston Mts., NW Ark., and flowing first N into SW Missouri, then generally SE through NE Arkansas to the Mississippi River. Its chief tributaries are the Black and Little Red rivers. Near its mouth, the White is joined to the Arkansas River by a cutoff channel. The White is navigable for shallow-draft vessels c.300 mi (480 km) upstream. Bull Shoals Dam (completed 1957), Table Rock Dam (1959), and Beaver Dam (1965) are major projects on the river. Bull Shoals Lake (111 sq mi/288 sq km), on the Ark.-Mo. line, is the largest reservoir. 2 River, 307 mi (494 km) long, rising near Muncie, E Ind., and flowing SW through Indianapolis to the Wabash River. With the White East Fork (282 mi/454 km long), its chief tributary, the White drains much of S Indiana. 3 River, 507 mi (816 km) long, rising in NW Nebraska and flowing N then E through S South Dakota to the Missouri River near Chamberlain. It drains much of the Badlands.

West River, China: see Xi.

Upper Missouri River Breaks National Monument: see National Parks and Monuments (table).

Upper Delaware Scenic and Recreational River: see National Parks and Monuments (table).

Tlikakila Wild River: see Lake Clark National Park and Preserve.

Tinayguk Wild River: see Gates of the Arctic National Park and Preserve.

Stones River National Battlefield: see National Parks and Monuments (table).

South River, borough (1990 pop. 13,692), Middlesex co., E N.J.; settled 1720, inc. 1898. Manufactures include clothing, furniture, and handkerchiefs.

Smoky Hill River, c.560 mi (900 km) long, rising on the Great Plains, E Colo., and flowing E across Kansas to join the Republican River and form the Kansas River at Junction City. The Saline River is its chief tributary. The Smoky Hill basin is included in the Missouri River basin project. Kanopolis Dam (completed 1948) and Cedar Bluff Dam (1951) are used for irrigation and flood control.

Salt River valley, irrigated region around the lower course of the Salt River, which rises in mountain streams near the Mogollon Rim of the Mogollon Plateau and flows southwest to join the Gila River in S central Arizona. Phoenix is the main city of the latter Ariz. region. Native Americans used the Salt River for irrigation many centuries ago. In the 19th cent., American settlers began irrigated farming in the valley, and the Mormons used some of the old Native American canals at Mesa, Ariz. The Salt River project, the first large irrigation scheme undertaken under the Federal Reclamation Act of 1902, is one of the most economically successful projects in North America. It began in 1903 when construction started on the Roosevelt Dam in a canyon E of Phoenix. The dam, forming Roosevelt Lake behind it, impounds enough water to irrigate fields for about two years even if no rain falls. Other dams were built between 1922 and 1946 to supply water and power. The region is a rich producer of citrus fruits, lettuce, melons, and other crops. A major factor in the Salt River project's success is the long season without frost; the climate also makes this area an attractive winter resort.

Salt River Bay National Historical Park and Ecological Preserve: see National Parks and Monuments (table).

Salmon Wild River: see Kobuk Valley National Park.

Rocky River, city (1990 pop. 20,410), Cuyahoga co., NE Ohio, a suburb of Cleveland, on Lake Erie; settled 1815, inc. 1903. Chiefly residential, it is noted for its scenic atmosphere and quiet charm.

Rock River, c.285 mi (460 km) long, rising in SE Wisc. and flowing SW through NW Ill. to the Mississippi River near Rock Island. It flows through a fertile farm area. Rockford, Ill., is the chief city on the river. Lake Koshkonong (c.20 sq mi/50 sq km) is a natural widening of the river.

River Rouge, city (1990 pop. 11,314), Wayne co., SE Mich., an industrial suburb of Detroit, on the Detroit and Rouge rivers; settled c.1817, inc. 1899. It is a port of entry, with automobile, shipbuilding, and marine engineering industries. Steel and paper products are also manufactured. The city grew in the 1920s with the expansion of the Ford Motor Company in the area; however, River Rouge and its automobile industry suffered in the late 20th cent.

River Grove, village (1990 pop. 9,961), Cook co., NE Ill., a suburb of Chicago on the Des Plaines River; inc. 1888. Sports equipment and wire cables are made.

River Forest, residential village (1990 pop. 11,669), Cook co., NE Ill., a suburb of Chicago, on the Des Plaines River; inc. 1880. It is the seat of Dominican Univ. and Concordia Univ. Several homes there were designed by Frank Lloyd Wright.

River Edge, residential borough (1990 pop. 10,603), Bergen co., NE N.J., on the Hackensack River; inc. 1894.

River Brethren, name used to designate certain Christian bodies originating in 1770, during a revival movement among German settlers in E Pennsylvania. In the 1750s, Mennonite refugees from Switzerland had established their homes near the Susquehanna River. Their religious leaders, Jacob and John Engle, became associated with the revival, and their followers came to be known as the River Brethren, possibly because they were baptized in the Susquehanna upon joining the brotherhood. Several factions of the River Brethren withdrew in the mid-19th cent., including the Yorker Brethren and the United Zion Church, while the main body took the name Brethren in Christ, by which a group of Mennonites is also known. The Brethren practice trine (triple, in allusion to the Trinity) immersion and foot washing, adhere to plain dress, and oppose war, alcohol, tobacco, and worldly pleasures. There were about 11,000 members in the United States and Canada in 1992. They carry out missionary work in Asia and Africa.

Red River Settlement, agricultural colony in present Manitoba, North Dakota, and Minnesota. It was the undertaking of Thomas Douglas, 5th earl of Selkirk. Wishing to relieve the dispossessed and impoverished in Scotland and Northern Ireland, he secured enough control of the Hudson's Bay Company to obtain from it a grant of land called Assiniboia. This project met opposition from the very start, principally from the North West Company, but also from the fur traders in the Hudson's Bay Company. Despite efforts to discourage the colony, Miles Macdonnell, a Selkirk man, brought a small group to the colony in 1812. The determined hostility of the North West Company mounted, especially after the company men had won the half-breeds, or métis, entirely to their side. By cajolery and threat they persuaded settlers to desert, but a new group of settlers came, and the colony was restored in 1815. North West Company men and half-breeds now resorted to violence on a large scale, killing 22 in the massacre of Seven Oaks (June 19, 1816). On hearing the news of the massacre, Selkirk fell upon the North West Company post, Fort William, and seized it. Other attacks followed. The result of these moves was a series of court charges and countercharges that impoverished Selkirk and helped to bring about the union (1821) of the Hudson's Bay Company and the North West Company. Agriculture had by this time been firmly established on the Western plains, and the Red River settlements were to grow and flourish. See Riel, Louis.

Red River Rebellion: see Riel, Louis.

Red River, Chinese Yuan Chiang, Vietnamese Song Hong, chief river of N Vietnam, 730 mi (1,175 km) long, rising in Yunnan prov., S China, and flowing southeast, in deep, narrow gorges, through N Vietnam to form a great delta before entering the Gulf of Tonkin. The river carries a large quantity of silt, rich in iron oxide, that gives it a red color. Northwest of Hanoi the river flows onto the coastal plain and receives the Clear and Black rivers, its chief tributaries. The Red River delta, c.75 mi (120 km) long and 75 mi wide, is the economic center of N Vietnam, whose chief port, Haiphong, is on the delta's north branch. Rice is the principal crop of the river valley; wheat, beans, rapeseed, corn, and subtropical crops are also grown. The Red River has an irregular flow and is subject to flooding, especially during the June-October high water period; dikes and canals protect the delta from floodwaters. A railroad and highway follow the Red River valley, an important transportation route linking China and Vietnam.

Red River. 1 River, 1,222 mi (1,967 km) long, southernmost of the large tributaries of the Mississippi River. It rises in two branches in the Texas Panhandle and flows SE between Texas and Oklahoma and between Texas and Arkansas to Fulton, Ark. It then turns southward, enters Louisiana, and crosses SE to the Atchafalaya and the Mississippi rivers. In Texas it flows rapidly through a canyon in semiarid plains, but later in its course it waters rich red-clay farm lands (whence the name Red). Dams on the river include the Denison Dam (completed 1943), which impounds Lake Texoma, one of the largest reservoirs in the United States. For many years navigation was difficult on the lower course of the Red River due to fallen trees that floated downstream and collected behind obstructions, forming rafts. The Great Raft, a 160-mi (257-km) log-jam built through the centuries, was cleared from the river in the mid-1800s. The river is now navigable for small ships to above Natchitoches, La. There are many lakes along the lower part of the river, and reservoirs serve as flood-control units on its tributaries. 2 River, often called the Red River of the North, c.310 mi (500 km) long, formed N of Lake Traverse, NE S.Dak., by the confluence of the Bois de Sioux and the Otter Tail rivers. It flows N between Minnesota and North Dakota and crosses the Canadian border into Manitoba, emptying into Lake Winnipeg. The river drains the principal spring wheat-growing area of the United States and Canada—the rich Red River valley region, the bed of the ancient Lake Agassiz. Its chief tributary is the Assiniboine River.

Plate, River: see Plata, Río de la.

Pearl River, uninc. village (1990 pop. 15,314), Rockland co., SE N.Y., near the N.J. line. It is a residential suburb of New York City, and a computer and telecommunications research and development center.

Orange River, chief river of S Africa, c.1,300 mi (2,090 km) long, rising in the Maluti Mts., N Lesotho. It flows SW through Lesotho, then meanders northwest and west through central South Africa, forming the SW boundary of Free State and part of the South Africa-Namibia line before entering the Atlantic Ocean at Oranjemund. The Vaal River is its chief tributary. The lower Orange River flows through the southern part of the Kalahari and Namib deserts; in very dry years it does not reach the sea. At the mouth of the river are rich alluvial diamond beds. Shoals, falls (Aughrabies Falls is 400 ft/122 m high), irregular flow, and a sandbar at its mouth limit navigation, but the river is used extensively for irrigation. The South African Orange River Project, which includes the Gariep and Vanderkloof dams, provides water for irrigation, hydroelectric power generation, and municipal water supplies. Tunnels divert water to the Great Fish and Sundays rivers.

Obed Wild and Scenic River: see National Parks and Monuments (table).

North Fork of the Koyukuk Wild River: see Gates of the Arctic National Park and Preserve.

New River Gorge National River: see National Parks and Monuments (table).

New River, c.320 mi (510 km) long, rising in the Blue Ridge, NW N.C. It flows NE through SW Virginia, then NW into West Virginia where it joins with the Gauley River to form the Kanawha River. It is used extensively to generate electricity. Bluestone Dam (completed 1952), near Hinton, W.Va., provides flood control and power, and its reservoir extends 36 mi (58 km) upstream. The New River Bridge, built across the River Gorge, is the largest steel-arch bridge in the United States.

Mulchatna Wild River: see Lake Clark National Park and Preserve.

Missouri River basin project, comprehensive plan authorized in 1944 for the coordinated development of water resources of the Missouri River and its tributaries, draining an area of c.513,300 sq mi (1,329,400 sq km) in Nebraska, Montana, South Dakota, North Dakota, Wyoming, Kansas, Missouri, Colorado, Iowa, and Minnesota. The program provided for the construction of 112 dams with a storage capacity of almost 35 million gal/132 million liters; 4,300,000 acres (1,740,000 hectares) of irrigated land; 2.6 million kilowatts of hydroelectric generating capacity; a 9-ft (2.7-m) navigable channel on the Missouri River from Sioux City to its mouth; control of floods and sedimentation; protection of fish and wildlife; and development of recreational facilities and industrial and municipal water supplies. Seven main-stem dams on the Missouri were completed (Fort Peck, Garrison, Oahe, Big Bend, Fort Randall, Gavins Point, and Canyon Ferry), and 80 other dams were built on tributaries. The program has been modified and expanded over the years and is integrated with other projects for the region, including the Colorado-Big Thompson project, the Shoshone project, and the North Platte project. Although the project created a navigation channel on the lower Missouri, the fish and wildlife there were greatly reduced.

Mississippi National River and Recreation Area: see National Parks and Monuments (table).

Middle River, uninc. town (1990 pop. 24,616), Baltimore co., N Md. It is an industrial and residential suburb of Baltimore.

Little River Canyon National Preserve: see National Parks and Monuments (table).

Little Red River, 105 mi (169 km) long, rising in the Boston Mts., NW Ark., and flowing SE to the White River. Greers Dam and reservoir (completed 1964) provide flood control and hydroelectric power.

Kobuk Wild River: see Gates of the Arctic National Park and Preserve.

Knife River Indian Villages National Historic Site: see National Parks and Monuments (table).

John Wild River: see Gates of the Arctic National Park and Preserve.

Indian River, lagoon, c.100 mi (160 km) long, E Fla., parallel to the east coast from N of Titusville to Stuart. Along the lagoon a variety of citrus and vegetable products are grown and transported by small boats to towns on its waterway and those further inland. The river's coasts have been marked by housing developments, especially for retired communities and for vacationers. Notable resort towns along the Indian's shores include Titusville, Vero Beach, Melbourne, and Ft. Pierce.

Hudson River school, group of American landscape painters, working from 1825 to 1875. The 19th-century romantic movements of England, Germany, and France were introduced to the United States by such writers as Washington Irving and James Fenimore Cooper. At the same time, American painters were studying in Rome, absorbing much of the romantic aesthetic of the European painters. Adapting the European ideas about nature to a growing pride in the beauty of their homeland, for the first time a number of American artists began to devote themselves to landscape painting instead of portraiture. They were particularly attracted by the grandeur of Niagara Falls and the scenic beauty of the Hudson River valley, the Catskills, and the White Mts. The works of these artists reflected a new concept of wilderness—one in which man was an insignificant intrusion in a landscape more beautiful than fearsome. First of the group of artists properly classified with the Hudson River school was Thomas Doughty; his tranquil works greatly influenced later artists of the school. Albert Bierstadt glorified the Rocky Mts. in the West, working in the same manner as the painters in the East. Thomas Cole, whose dramatic and colorful landscapes are among the most impressive of the school, may be said to have been its leader during the group's most active years. Among the other important painters of the school are Asher B. Durand, J. F. Kensett, S. F. B. Morse, Henry Inman, Jasper Cropsey, Frederick E. Church, and, in his earlier work, George Inness. See articles on individual painters.

Harlem River, navigable tidal channel, 8 mi (12.9 km) long with Spuyten Duyvil Creek, in New York City, SE N.Y., separating Manhattan from the Bronx. Connecting the Hudson and East rivers, it is a shipping shortcut between Long Island Sound and river ports north of New York City. Several railroad and many street bridges span the river.

Green River. 1 River, 370 mi (595 km) long, rising in central Ky. and flowing generally NW, through Mammoth Cave National Park, to the Ohio River near Evansville, Ind. Locks and dams make the Green River navigable upstream to the park. 2 River, 730 mi (1,175 km) long, rising near the Continental Divide, W Wyo., and flowing generally S through W Wyo., NW Colo., and E Utah to the Colorado River in Canyonlands National Park, SE Utah; it is the largest tributary of the Colorado. Most of its course flows through deep canyons, including Canyon of the Lodore in Dinosaur National Monument (see National Parks and Monuments, table). The White, Yampa, and San Rafael rivers are its main tributaries. The Colorado River storage project of the U.S. Bureau of Reclamation has extensively developed the Green River basin for irrigation, mining, and hydroelectric power; Flaming Gorge Dam, NE Utah, is the major unit in this project.

Great Egg Harbor Scenic and Recreational River: see National Parks and Monuments (table).

Grand River Dam: see Pensacola Dam.

Grand River, c.165 mi (270 km) long, rising in the highlands of the Ontario Peninsula, S Ont., Canada, and flowing S past Kitchener and Brantford, then SE to Lake Erie at Port Maitland. It is navigable for c.70 mi (110 km) upstream. The river drains one of the most populated regions of Canada.

Grand River. 1 River, 260 mi (418 km) long, rising in S Mich. and flowing N to Lansing, then NW to Lake Michigan at Grand Haven. It is the longest river in the state and is navigable to the city of Grand Rapids, which grew there because of the availability of waterpower. 2 River, rising in SW N.Dak. and flowing 209 mi (336 km) SE through S.Dak. to the Missouri River near Mobridge. Shadehill Dam (1951), located on the river, was built for flood control and irrigation as part of the Missouri River basin project. 3 River in Okla.: see Neosho, river; Pensacola Dam.

Gauley River National Recreation Area: see National Parks and Monuments (table).

French Broad River, 210 mi (338 km) long, rising in the Blue Ridge Mts., W N.C., and flowing N and then NW to Knoxville, E Tenn., where it joins with the Holston to form the Tennessee River. The French Broad River was an important settlers' route from the southeast coastal states into Tennessee during the colonial period. On the river is Douglas Dam, part of the Tennessee Valley Authority, forming Lake Douglas, which is used for flood control.

Fall River, industrial city (1990 pop. 92,703), Bristol co., SE Mass., a port of entry on Mt. Hope Bay, at the mouth of the Taunton River; settled 1656, set off from Freetown 1803, inc. as a city 1854. It was once the foremost cotton textile center in the United States; the first cotton mill was built in 1811. Textiles and clothing are the leading manufactures, and a variety of products are made, including metals and chemicals. The Bradford Durfee College of Technology is in Fall River. The U.S.S. Massachusetts, the state's official World War II memorial, is berthed in the harbor. The city was the scene (1892) of the famous trial of Lizzie Borden, who was acquitted of murdering her parents in the family's home there.

East River, tidal strait, 16 mi (26 km) long and 600-4,000 ft (183-1,219 m) wide, connecting Upper New York Bay and Long Island Sound, New York City, and separating the boroughs of Manhattan and the Bronx from Brooklyn and Queens. The East River is linked with the Hudson River at the northern end of Manhattan island by the Harlem River. Roosevelt (formerly Welfare), Wards, Randalls, Rikers, North Brother, and South Brother islands, all located in the East River, have city institutions, parks, and recreation areas. Roosevelt Island was developed as a residential area in the early 1970s. Hell Gate, at the junction of the Harlem and East rivers, was named for its treacherous currents and rocky reefs (now removed). Eight bridges, including the historic Brooklyn Bridge, span the river; subway, railroad, and vehicular tunnels pass beneath it.

Delaware River Basin Compact, providing for the utilization and development of the water resources of the Delaware River basin. In 1961 the federal government and the states of Delaware, Pennsylvania, New Jersey, and New York agreed to form a partnership in a 100-year building program under the supervision of the Delaware River Basin Commission. Dams and reservoirs furnishing hydroelectricity, flood control, water conservation, recreation, and wildlife refuge are planned. A minimum flow rate was established to prevent saltwater intrusion in the lower river.

Delaware National Scenic River: see National Parks and Monuments (table).

Dead River, 45 mi (72 km) long, rising on the Canadian border, NW Maine, and flowing northeast through a hunting and fishing region to the Kennebec River. Long Falls Dam, on the Dead River, generates hydroelectricity.

Colorado River storage project, a multipurpose plan, undertaken by the U.S. Bureau of Reclamation in 1956, to control the flow of the upper Colorado and its tributaries and to aid in the development of the rugged, remote upper Colorado River basin; includes parts of Wyo., Utah, Colo., Ariz., and N.Mex. The Colorado River Compact of 1922 established the division between the upper and lower basins and stipulated that the upper basin's water consumption be contingent on the delivery of a set amount of water to the lower basin. Since the flow of the Colorado is erratic, a storage project was needed to maintain an even flow of water to the lower basin in dry years (the estimate of the average flow of the river, however, was based on what historically was a relatively wet period, and was 10% to 25% more than long-term estimates now indicate). A series of dams regulates stream flow, provides storage reservoirs, creates hydroelectric power, and irrigates both new and previously developed acreage. The four major units of the project are Glen Canyon Dam, on the Colorado River in Arizona; Flaming Gorge Dam, on the Green River in Utah; Navajo Dam, on the San Juan River in New Mexico; and the Curecanti dams on the Gunnison River in Colorado. The three reservoirs of the Curecanti unit are included in the Curecanti National Recreation Area (see National Parks and Monuments, table). There are 11 authorized participating projects, including the Central Utah project.

Chilikadrotna Wild River: see Lake Clark National Park and Preserve.

Chattahoochee River National Recreation Area: see National Parks and Monuments (table).

Charley Wild River: see Yukon-Charley Rivers National Preserve.

Charles River Bridge Case, decided in 1837 by the U.S. Supreme Court. The Charles River Bridge Company had been granted (1785) a charter by the state of Massachusetts to operate a toll bridge. The state later authorized (1828) a competing bridge that would eventually be free to the public. The Charles River Bridge Company brought suit against the competing company, claiming that the state charter had given it a monopoly. The court upheld the state's authorization to the other company, holding that since the original charter did not specifically grant a monopoly, the ambiguity in the contract would operate in favor of the public, thus allowing a competing bridge. The holding modified the Dartmouth College Case, which held that a state could not unilaterally amend a charter.

Cape Fear River, 202 mi (325 km) long, formed in E central N.C. by the junction of the Deep and Haw rivers, and flowing southeast to enter the Atlantic Ocean S of Wilmington and N of Cape Fear; longest river entirely within North Carolina. Dams and locks make the river navigable to Fayetteville, but its valley is especially prone to flooding, as happened after Hurricane Floyd (1999).

Cane River Creole National Historical Park and Heritage Area: see National Parks and Monuments (table).

Buffalo National River, Ark.: see National Parks and Monuments (table).

Bluestone National Scenic River: see National Parks and Monuments (table).

Blind River, town (1991 pop. 3,355), S Ont., Canada, on North Channel of Lake Huron. It is the center of the Algoma uranium fields. Just to the east of the town is Ontario's first uranium mine (1955).

Black River. 1 River rising in SE Mo. and flowing c.300 mi (480 km) SE, then SW to the White River near Newport, Ark. It is partly navigable. Clearwater Dam is on the river near Piedmont, Mo. 2 River of N N.Y., c.120 mi (190 km) long, rising in the Adirondack Mts. and flowing mainly N and W to Black River Bay, an inlet of Lake Ontario. Its falls provide power for factories and mills. 3 River, c.160 mi (260 km) long, rising in central Wis. and winding SW to the Mississippi River at La Crosse, Wis. It has been used to transport lumber, coal, and petroleum products. Big Manitou Falls, the highest falls in Wisconsin (165 ft/50 m), are in the river.

Big South Fork National River and Recreation Area: see National Parks and Monuments (table).

Arctic Red River, c.310 mi (500 km) long, rising in the Mackenzie Mts. of W Northwest Territories, Canada, and flowing generally NW to the Mackenzie River. At its mouth are a post of the Royal Canadian Mounted Police and the village of Tsiigehtchic, formerly Arctic Red River.

Alatna Wild River: see Gates of the Arctic National Park and Preserve.

Alagnak Wild River: see National Parks and Monuments (table).

Low-lying plain composed of stream-borne sediments deposited by a river at its mouth. Deltas have been important to humankind since prehistoric times. Sands, silts, and clays deposited by floodwaters were extremely productive agriculturally; and major civilizations flourished in the deltaic plains of the Nile and Tigris-Euphrates rivers. In recent years geologists have discovered that much of the world's petroleum resources are found in ancient deltaic rocks. Deltas vary widely in size, structure, composition, and origin, though many are triangular (the shape of the Greek letter delta).

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Natural stream of water that flows in a channel with more or less defined banks. Rivers are a fundamental link in the hydrologic cycle, and they play a major role in shaping the surface features of the Earth. Even apparently arid desert regions are greatly influenced by river action when periodic floodwaters surge down usually dry watercourses. River flow is sustained by the difference between water input and output. Rivers are fed by overland runoff, groundwater seepage, and meltwater released along the edges of snowfields and glaciers. Direct precipitation contributes only very small amounts of water. Losses of river water result from percolation into porous and permeable rock, gravel, or sand; evaporation; and ultimately outflow into the ocean.

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or Huang Ho English Yellow River

River, northern, central, and eastern China. The second longest river in China and one of the world's longest, it flows 3,395 mi (5,464 km) from the Plateau of Tibet generally east to the Yellow Sea (Huang Hai). In its lower reaches it has often overflowed its banks, flooding vast areas of rich farmland. Its outlet has shifted over the years to enter the Yellow Sea at points as far apart as 500 mi (800 km). Irrigation and flood-control works have been maintained for centuries, and dams, begun in the mid-1950s, exploit the river's hydroelectric potential.

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Mountain range, central Rocky Mountains, west-central Wyoming, U.S. The range extends for 100 mi (160 km) northwest-southeast to the Sweetwater River and is part of the Continental Divide. It contains many peaks above 12,000 ft (3,658 m); the highest is Gannett Peak at 13,804 ft (4,207 m). The Oregon Trail ran through the historic South Pass (7,743 ft, or 2,360 m). Parts of Bridger and Shoshone national forests and Wind River Indian Reservation are in the range. The Wind River flows from the eastern side into the Bighorn River; the Green River rises on its western slopes.

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River, Arkansas, U.S. It rises in the Boston Mountains in northwestern Arkansas, flows north into southern Missouri, then bends southeast and reenters Arkansas. It continues south to join the Arkansas River near its confluence with the Mississippi River. It is 685 mi (1,102 km) long.

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Russian Zapadnaya Dvina Latvian Daugava

River, north-central Europe. It rises in Russia's Valdai Hills and flows 632 mi (1,020 km) in a great arc south through Russia and into Belarus and then northwest across Latvia. It discharges into the Gulf of Riga on the Baltic Sea. An important water route since early times, connected in its upper reaches by easy portages to the Dnieper, Volga, and Lovat-Volkhov river systems, it constituted part of the great trade route from the Baltic region to Byzantium and to the Arabic east. Rapids and the presence of dams have restricted navigation on it.

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River, western Russia. Europe's longest river and the principal waterway of western Russia, it rises in the Valdai Hills northwest of Moscow and flows 2,193 mi (3,530 km) southeastward to empty into the Caspian Sea. It is used for power production, irrigation, flood control, and transportation. The river has played an important part in the life of the Russian people, and in Russian folklore it is characteristically named “Mother Volga.”

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Swedish Torneälv

Northernmost river of Sweden. Issuing from Torne Lake near the Norwegian border, it flows southeast and south for 354 mi (570 km) to the Gulf of Bothnia. The lower course, strewn with rapids and mostly non-navigable, forms a section of the Sweden-Finland boundary. It is known for its salmon.

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ancient Tamesis

Principal river of England. It rises in the Cotswolds in Gloucestershire and winds 205 mi (330 km) eastward across south-central England into a great estuary, through which it empties into the North Sea. It is tidal for about 65 mi (104 km). Known by the Romans and by early English chroniclers, it has been celebrated by bards throughout history. One of the world's most important commercial waterways, it is navigable by large vessels to London.

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River, north-central U.S. It rises in southeastern Wisconsin and flows across the northwestern corner of Illinois, emptying into the Mississippi River at Rock Island, Ill.; it is 300 mi (480 km) long. The bottomlands along the lower course are subject to spring floods and require levee protection.

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ancient Tamesis

Principal river of England. It rises in the Cotswolds in Gloucestershire and winds 205 mi (330 km) eastward across south-central England into a great estuary, through which it empties into the North Sea. It is tidal for about 65 mi (104 km). Known by the Romans and by early English chroniclers, it has been celebrated by bards throughout history. One of the world's most important commercial waterways, it is navigable by large vessels to London.

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Estuary of the Paraná and Uruguay rivers, between Uruguay and Argentina. It is about 180 mi (290 km) long, with a maximum width of 136 mi (219 km) at its mouth, but it narrows gradually to the northwest as it approaches Buenos Aires. Discovered by the Spanish in 1516, it was explored by Ferdinand Magellan in 1520 and by Sebastian Cabot (1526–29). The first permanent settlement in the area was at Asunción in 1537.

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or Great Ouse

River, central and eastern England. It rises in Northamptonshire and flows 156 mi (251 km) past Buckingham, Bedford, Huntington, and St. Ives to Earith, then to the North Sea. Locks make the river navigable upstream to Bedford.

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or Lower Avon

River, southwestern England. Rising in Gloucestershire, it flows 75 mi (121 km) southwest through Bristol and into the Bristol Channel at Avonmouth, Bristol's port. Below Bristol it has cut through a limestone ridge to form Clifton Gorge, noted for its suspension bridge.

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River, south-central U.S. It rises in the high plains of eastern New Mexico and flows southeast across Texas and Louisiana to a point northwest of Baton Rouge, where it enters the Atchafalaya River. It is 1,290 mi (2,080 km) long and forms a part of Texas's borders with Oklahoma and Arkansas. In Texas it was the site of the Red River Indian War (1874).

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ancient Padus.

River, northern Italy. The country's longest river, it is about 405 mi (652 km) long. It rises in the Cottian Alps on the western frontier and flows northeast to Turin, then east across Piedmont and Lombardy into the Adriatic Sea. Its delta is one of the most complex of any European river, with at least 14 mouths. It is navigable from its mouth to Pavia. Industrial cities in its valley include Milan, Padua, and Verona. It has suffered devastating autumn floods, including those in 589, 1438, 1951, and 1966.

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River, central Mississippi, U.S. It flows southwest through Jackson, then into Louisiana and the Gulf of Mexico. About 410 mi (660 km) long, it forms the boundary between Mississippi and Louisiana. Honey Island Swamp, lying in the mid-delta area southwest of Picayune, Miss., is noted for its wildlife and fishing.

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or Great Ouse

River, central and eastern England. It rises in Northamptonshire and flows 156 mi (251 km) past Buckingham, Bedford, Huntington, and St. Ives to Earith, then to the North Sea. Locks make the river navigable upstream to Bedford.

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River, southern Africa. It rises in the Lesotho Highlands as the Sinqu River and flows west as the Orange across South Africa. It passes the southern edge of the Kalahari Desert and winds through the Namib Desert before draining into the Atlantic Ocean in South Africa. It forms the border between South Africa and Namibia. It is about 1,300 mi (2,100 km) long. There are some irrigated sections along the river and many dams but no large towns.

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River, southwestern Virginia and southern West Virginia, U.S. It is formed in North Carolina and flows north across Virginia into West Virginia, where it joins the Gauley River to form the Kanawha River. It is about 255 mi (410 km) long and is spanned by one of the longest steel-arch bridges in the world, the New River Gorge bridge near Fayetteville, W.Va., whose main span is 1,700 ft (518 m).

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ancient Halys River

River, central and north-central Turkey. The longest river wholly within Turkey and the largest in Anatolia, it rises in north-central Turkey and flows southwestward. It turns north and empties into the Black Sea after a total course of 734 mi (1,182 km). Unsuitable for navigation, it is a source of irrigation and hydroelectricity for the region.

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U.S. landscape painters of several generations, active circa 1825–70. The first of them were inspired by the natural beauty of New York's Hudson River valley and Catskill Mountains. The leading figures were Thomas Cole, Asher B. Durand, and Thomas Doughty (1793–1856). Others, such as Frederic Edwin Church and George Inness, had studied in Europe and found inspiration in the grandiose landscapes of J.M.W. Turner. By mid century they were widely admired for their depictions of a common theme, the splendour of the untamed U.S. landscape. The name Hudson River school, applied retrospectively, is extended to artists of the same vision who painted imposing scenes of the Rocky Mountains, Grand Canyon, and Yosemite Valley. The first native school of painting in the U.S., it remained the dominant school of landscape painting throughout the 19th century.

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River, western U.S. It flows from western Wyoming south into Utah, where it turns east to make a loop through the northwestern corner of Colorado. Turning south in Utah, it enters the Colorado River in Canyonlands National Park after a course of 730 mi (1,175 km). Originally known as the Spanish River, it was renamed in 1824, probably for its colour, derived in places from green soapstone banks along its course.

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formerly Glåma River

River, eastern Norway. The longest river in Scandinavia, it rises in a series of small streams near the Swedish-Norwegian border. It flows south, then west into Lake Øyeren. From there it continues south to Sarpsborg and enters Oslo Fjord at Fredrikstad, after a course of 372 mi (599 km). It is a major source of hydroelectric power. It is navigable up to Sarpsfoss, the waterfall at Sarpsborg.

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Hindi Ganga

River, northern India and Bangladesh. Held sacred by followers of Hinduism, it is formed from five headstreams rising in Uttaranchal state. On its 1,560-mi (2,510-km) course, it flows southeast through the Indian states of Uttar Pradesh, Bihar, and West Bengal. In central Bangladesh it is joined by the Brahmaputra and Meghna rivers. Their combined waters (called the Padma River) empty into the Bay of Bengal and form a delta 220 mi (354 km) wide, which is shared by India and Bangladesh. Its plain is one of the most fertile and densely populated regions in the world. Millions of Hindus bathe in the river annually at special holy places (tirthas). Many cast the ashes of their dead into its waters, and cremation temples are found along its banks in numerous places.

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River, western North Carolina, U.S. Rising in the Blue Ridge and flowing 210 mi (340 km) north through the Great Smoky Mountains into Tennessee, it then turns west to join the Holston River near Knoxville, forming the Tennessee River. Douglas Dam, part of the Tennessee Valley Authority, is on the river near the junction.

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Navigable tidal strait in the U.S. linking Upper New York Bay with Long Island Sound in New York City. It separates Manhattan and the Bronx from Brooklyn and Queens. About 16 mi (26 km) long and 600–4,000 ft (200–1200 m) wide, it connects with the Hudson River via the Harlem River and Spuyten Duyvil Creek at the northern end of Manhattan Island. Roosevelt (formerly Welfare), Wards, Randalls, and Rikers islands are in the East River, which has numerous port facilities.

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ancient Druentia.

River, southeastern France. The principal river draining the French side of the Alps toward the Mediterranean, its origin is in the Montgenèvre region. To its confluence with the Rhône River below Avignon, it is 189 mi (304 km) long. It is the site of extensive hydroelectric projects that were established after World War II.

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or Donnai River

River, southern Vietnam. Rising in the central highlands, it flows southwest for about 300 mi (480 km), joining the Saigon River northeast of Ho Chi Minh City and combining with it and other streams to form an estuary north of the Mekong delta.

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or Maenam River

River, Thailand. Flowing south from the highlands on the country's northern border to the head of the Gulf of Thailand near Bangkok, it is some 225 mi (365 km) long and is Thailand's principal river. It is important for the transport of the country's exports. It also forms a highly productive agricultural valley. The name strictly applies only to the river's lower course, which begins at the confluence of the Nan and Ping rivers and is 140 mi (225 km) long.

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River, central and southeastern North Carolina, U.S. Formed by the confluence of the Deep and Haw rivers, it flows southeast about 200 mi (320 km) to enter the Atlantic Ocean near Southport at Cape Fear. The southern estuary forms part of the Atlantic Intracoastal Waterway. A series of locks and dams makes the river navigable from Wilmington to Fayetteville.

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River, Central and South Asia. From its headsprings in the Tibet Autonomous Region of China (as the Yarlung River), it flows across southern Tibet to break through the Himalayas in great gorges (where it is known as the Dihang). It flows southwest through the Assam Valley and south through Bangladesh (where it is known as the Jamuna). There it merges with the Ganges (Ganga) to form a vast delta. About 1,800 mi (2,900 km) long, the river is an important source for irrigation and transportation. Its upper course was long unknown, and its identity with the Zangbo was only established by exploration in 1884–86.

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ancient Chrysorrhoas

River, western Syria. It flows about 50 mi (80 km) from the Anti-Lebanon Mountains past Damascus. Throughout history, channels have been cut at different levels parallel to the main branch of the river to divert its flow. The channels (of Nabataean, Aramaean, and, especially, Roman origin) fan out as they reach Damascus, irrigating a large area. This system created Al-Ghūtsubdotah, a fertile belt near Damascus.

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or Lower Avon

River, southwestern England. Rising in Gloucestershire, it flows 75 mi (121 km) southwest through Bristol and into the Bristol Channel at Avonmouth, Bristol's port. Below Bristol it has cut through a limestone ridge to form Clifton Gorge, noted for its suspension bridge.

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Longest river in Greece. It rises in the Pindus Mountains and flows south 140 mi (220 km) to the Ionian Sea. Hydroelectric dams harness its waters at Kastraki and Kremasta. In ancient mythology, Achelous was a protean river god, who was vanquished by Hercules.

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