Argentina is triangular in shape and stretches c.2,300 mi (3,700 km) from its broad northern region near the Tropic of Capricorn to Tierra del Fuego, an island shared with Chile, in the south. On the northeast, Argentina fronts on the Río de la Plata (an estuary and one of the major waterways of the Western Hemisphere), which separates Argentina from S Uruguay; its tributaries also act as international boundaries—the Uruguay River, with W Uruguay and S Brazil, and the Paraná, Paraguay, and Pilcomayo rivers, with Paraguay. The northwest boundary with Bolivia lies in the Gran Chaco and the Andes Mts. The western boundary with Chile follows the crestline of the Andes. The Atlantic Ocean borders Argentina on the east; there, off S Argentina, are the Falkland Islands ( Islas Malvinas ), and the South Georgia, South Sandwich, and South Orkney islands, all dependencies of Great Britain that are claimed by Argentina.
Argentina also claims a sector of Antarctica. The climate of Argentina varies from subtropical in the north to cold and windswept in the south, with temperate and dry areas found throughout much of the country. Precipitation, lowest along the E Andean slopes, increases markedly N and E across Argentina. The chief rivers of Argentina are the Paraná with its tributary, the Salado; the Colorado River; the Río Negro; and the Chubut.
Argentina may be divided into six geographical regions—the Paraná Plateau, the Gran Chaco, the Pampa (see under pampas), the Monte, Patagonia, and the Andes Mts. The Paraná Plateau in the extreme northeast is an extension of the highlands of S Brazil. It is the wettest part of Argentina and has a dense forest cover; tobacco, timber, and yerba maté are the chief products there. The spectacular Iguaçu Falls are in a national park located at the point where Argentina, Brazil, and Paraguay meet.
In N Argentina the Gran Chaco, with the physiographically similar Mesopotamia (between the Paraná and Uruguay rivers), is a predominantly flat alluvial plain with a subtropical climate. The region is seasonally flooded, and marshlands remain for long periods during the year because of poor drainage. Livestock, cotton, and wood from the quebracho tree are the main products.
South of the Gran Chaco is the Pampa, a vast, monotonous natural grassland that extends to the Colorado River (roughly from lat. 30°S to 40°S) and is c.400 mi (640 km) wide from the Atlantic Ocean to the Andean foothills. The Pampa's deep, rich soil is the basic wealth of the country. The "Wet Pampa," the more humid eastern part of the region, is Argentina's principal agricultural area and produces most of the nation's exports. It is the granary of South America, with wheat, alfalfa, corn, and flax the principal crops. Cattle ranching is prevalent throughout the Pampa and especially in the southeast and north; sheep are also raised there. Dairying is important in the vicinity of Buenos Aires. The Pampa has the densest transportation network of roads and railroads in South America.
Most of the principal cities of Argentina and most of its industry are found in the region. Buenos Aires, a port city on the Río de la Plata, is one of the largest cities of South America and the chief industrial center and transportation hub of S South America; it is surrounded by smaller industrial cities. Elsewhere on the Pampa are La Plata, a meatpacking and oil-refining center; Rosario, the third largest city of Argentina, an iron and steel and oil-refining center, and a huge grain port on the Paraná River; Santa Fe, a northern commercial and industrial center at the junction of the Salado and Paraná rivers; Mar del Plata, a resort and fishing center on the Atlantic Ocean; and Bahía Blanca, the largest Argentine port directly on the Atlantic Ocean, a gateway to the S Pampa and the oil fields of Neuquén prov., and a meatpacking and wool-processing center. On the western edge of the Pampa is Córdoba, the nation's second largest city, which reflects the transition from the "Dry Pampa" to the Monte, the desolate Andean foothills.
The Monte, an arid region in the rain shadow of the Andes, has natural vegetation varying from short grasses in the east to cacti in the west. Scattered throughout the great arid stretches are small but highly productive oases such as Jujuy, Salta, Tucumán, San Juan, and Mendoza, which were settled from Peru and Upper Peru (Bolivia) in the second half of the 16th cent. The oases, whose growth and importance greatly increased after they were linked by railroad to the east coast, produce wine, sugar, fruits, and corn; stock raising is also carried on there. The varied mineral deposits of this region (especially oil, lead, zinc, tin, copper, and salt) are being exploited. Mendoza and Tucumán are major industrial areas engaged in food processing, oil refining, and chemical production.
Occupying the southern part of Argentina is Patagonia, a vast, bleak, and windswept dissected plateau. Several large rivers flow in deep valleys eastward across Patagonia to the sea. Sheep raising (chiefly for wool) and oil and natural gas production (the area around Comodoro Rivadavia is the chief oil-producing region of Argentina) are the principal economic activities of Patagonia. The poor soils of Patagonia and its cool and dry climate do not favor cultivation, although irrigated agriculture is practiced in the Negro and Colorado river valleys. Patagonia is sparsely populated and largely undeveloped, with a few small river-mouth ports on the Atlantic coast such as Viedma, Rawson, Puerto Deseado, and Río Gallegos. Ushuaia, Tierra del Fuego, on Canal Beagle, is the world's southernmost town.
The Andes Mts. region of Argentina, broad in the north, where it is similar to the Bolivian altiplano, and becoming narrower toward the south, extends along the length of Argentina's western border. The region, which contains some of the world's highest elevations outside Asia—including Aconcagua (22,835 ft/6,960 m high; the highest point of the Western hemisphere), Bonete, Tupungato, Mercedario, and Llullaillaco—acts as a barrier to the moist westerly winds, thus giving the eastern slopes of the Andes a desert condition that contrasts with the heavy snowfall on the higher elevations. There are timber and mineral resources, but they are not readily exploitable because of the region's inaccessibility. Cattle are raised on the grassy Andean foothills. There are many beautiful lakes in the region, especially where it merges with the Patagonian plateau; Lake Nahuel Huapí in Nahuel Huapí National Park, adjoining the Chilean lake district, is an attractive resort area.