North America

North America, third-largest continent, situated in the Western Hemisphere and bounded on the north by the Arctic Ocean, on the south by South America, on the west by the Pacific Ocean and Bering Sea, and on the east by the Atlantic Ocean. Besides the area covered by Canada and the United States, it includes Mexico and Central America, the islands of the Caribbean Sea, and Greenland.

Land and climate

North America, roughly triangular in shape, covers about 9,400,000 sq mi (24,346,000 sq km) with a coastline of about 190,000 mi (300,000 km). Hudson Bay in the north and the Gulf of Mexico in the south break into the triangle. The continent contains several regions of coastal and mountain ranges, and interior plains. The Great Divide formed by the crest of the Rocky Mountains creates 2 great groups of rivers. One group, including the Colorado, Columbia, Fraser, and Yukon rivers, flows west into the Pacific; the other, which includes the Mackenzie, St. Lawrence, Rio Grande, Missouri, and Mississippi rivers, drains into the Atlantic Ocean or the Gulf of Mexico.

North America's climate ranges from polar in the north to tropical in the south. Climatic differences account for a wide variety of vegetation on the continent, ranging from arctic tundra in Greenland, northern Canada, and much of Alaska, to desert scrub in the Mojave, Sonora, and other deserts of the southwestern United States and Mexico, to tropical rain forests in the lowlands of Central America. Coniferous forests cover much of Canada, the northern Pacific ranges, and the southeastern United States. In the Appalachians, mixed forests predominate, while deciduous forests are characteristic of the coastal plain and the eastern part of the Interior Plain. Grassland covers vast areas of the rest of it, including the Great Plains.

People

With a total population of about 276,000,000, North America ranks third among all the continents. The most heavily populated regions lie in the eastern United States, southeastern Canada, along the Pacific coasts of both these countries, and in Central America. Indians were North America's first inhabitants; today the largest concentration of Native Americans and mestizos (mixed Indian and Spanish ancestry) is found in mainland Central America. Africans and mulattos (mixed black and white descent), whose ancestors were brought from Africa as slaves, constitute a large proportion of the population of the Caribbean islands. In the United States, about 10% of the population are of African-American descent. Caucasians of European descent form the great majority of North Americans.

Early history

It is thought that about 25,000 years ago peoples from Mongolia moved out of Asia across a natural land bridge that then linked the Asian and North American continents, where the Bering Strait is today. These people are believed to be the ancestors of all Native North American groups. It is known that Eric the Red, a Norseman, reached Greenland from Iceland in about A.D. 980, and Leif Ericsson reputedly landed in Nova Scotia about 1000. The first permanent contacts made by Europeans came in the 15th century, when Christopher Columbus landed on Hispaniola (1492) in the Bahamas, and John and Sebastian Cabot explored the coast of Newfoundland (1497).