North America, third largest of the world’s continents, lying for the most part between the Arctic Circle and the Tropic of Cancer.

North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, or simply the Americas. Mainland North America is shaped roughly like a triangle, with its base in the north and its apex in the south; associated with the continent is Greenland, the largest island in the world, and such offshore groups as the Arctic Archipelago, the West Indies, Haida Gwaii (formerly the Queen Charlotte Islands), and the Aleutian Islands.

North America is bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the North Pacific Ocean. To the northeast Greenland is separated from Iceland by the Denmark Strait, and to the northwest Alaska is separated from the Asian mainland by the much narrower Bering Strait.

The name America is derived from that of the Italian merchant and navigator Amerigo Vespucci, one of the earliest European explorers to visit the New World. Although at first the term America was applied only to the southern half of the continent, the designation soon was applied to the entire landmass. Those portions that widened out north of the Isthmus of Panama became known as North America, and those that broadened to the south became known as South America.

North America contains some of the oldest rocks on Earth. Its geologic structure is built around a stable platform of Precambrian rock called the Canadian (Laurentian) Shield. To the southeast of the shield rose the ancient Appalachian Mountains; and to the west rose the younger and considerably taller Cordilleras, which occupy nearly one-third of the continent’s land area. In between these two mountain belts are the generally flat regions of the Great Plains in the west and the Central Lowlands in the east.