Continent, Western Hemisphere.
The third-largest continent on earth, it lies mostly between the Arctic Circle and the Tropic of Cancer . It is almost completely surrounded by bodies of water, including the Pacific Ocean, the Bering Strait, the Arctic Ocean, the Atlantic Ocean, and the Caribbean Sea and Gulf of Mexico. Area: 9,361,791 sq mi (24,247,039 sq km). Population (2001 est.): 454,225,000. Shaped like an inverted triangle, North America was apparently the first continent to achieve its current approximate size and shape. Its geologic structure is built around a stable platform of Precambrian rock called the Canadian Shield . To the southeast are the Appalachian Mountains and to the west are the younger and much taller Cordilleras. These mountains extend the length of the continent and occupy about one-third of the total land area. The Rocky Mountains constitute the eastern Cordillera. The highest point is Mount McKinley . The Mississippi River basin, including its major tributaries, the Missouri and Ohio , occupies more than one-eighth of the continent's total area. Generally temperate climatic conditions prevail. Arable land accounts for about one-eighth of the land area and forests for about one-third. English, the primary language of the U.S., predominates, followed by Spanish; French is spoken in parts of Canada. Most of the continent's population of European descent is found in the U.S. and Canada. Intermarriage between whites and Indians was common in Mexico, and mestizos constitute about three-fifths of the Mexican population. North America has a mixture of developed, partly developed, and developing economies, adequate reserves of most metallic resources, and the world's largest reserves of cadmium, copper, lead, molybdenum, silver, and zinc. It is the world's leading food producer, largely because of mechanized and scientific farming in the U.S. and Canada. Among the continent's democratically governed states are Canada, Mexico, Costa Rica, and the U.S. The nations of North America have sought hemispheric unity as members of the Organization of American States , which also includes South American countries. They also sought stronger economic ties, and in 1992 Canada, the U.S., and Mexico signed the North American Free Trade Agreement (NAFTA), which called for the elimination of most tariffs and other trade barriers between the three countries. The first inhabitants were American Indians , who migrated from Asia about 20,000 years ago. The greatest pre-Columbian civilizations were in Mesoamerica (see Mesoamerican civilization ) and included the Olmec , Maya , Toltec , and Aztec , who were conquered by the Spanish. The continent long remained sparsely settled and undeveloped. Beginning in the 17th century it underwent a profound transformation with the coming of Europeans and the Africans they introduced as slaves. The style of life became Latin American south of the Rio Grande and Anglo-American to the north, with enclaves of French culture in Canada and Louisiana. Slavery, practiced in the 16th19th centuries, added a significant minority culture of African origin, especially in the U.S. and the Caribbean (see West Indies ). The huge industrial economy of the U.S., its abundant resources, and its military strength give the continent considerable global influence.