North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and almost totally in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North
Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west by the North Pacific Ocean; South America lies to the southeast. North America covers an area of about 9,540,000 square miles, about 4.8% of the planet's surface or about 16.5% of its land area. As of July 2008, its population was estimated at nearly 529 million people. It is the third-largest continent in area, following Asia and Africa, and the fourth in population after Asia, Africa, and Europe.
Scientists have several theories as to the origins of the early human population of North America. The indigenous peoples of North America themselves have many creation myths, by which they assert that they have been present on the land since its creation.
Before contact with Europeans, the natives of North America were divided into many different polities, from small bands of a few families to large empires. They lived in several "culture areas", which roughly correspond to geographic and biological zones and give a good indication of the main lifeway or occupation of the people who lived there (e.g. the Bison hunters of the Great Plains, or the farmers of Mesoamerica). Native groups can also be classified by their language family (e.g. Athapascan or Uto-Aztecan). It is important to note that peoples with similar languages did not always share the same material culture, nor were they always allies.
Scientists believe that the Inuit people of the high Arctic came to North America much later than other native groups, as evidenced by the disappearance of Dorset culture artifacts from the archaeological record, and their replacement by the Thule people.
North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America (which is sometimes considered a single continent and North America a subcontinent). North America's only land connection to South America is at the Isthmus of Panama. The continent is generally delimited on the southeast by the Darién watershed along the Colombia-Panama border, or at the Panama Canal; according to other sources, its southern limit is the Isthmus of Tehuantepec, Mexico, with Central America tapering and extending southeastward to South America. Before the Central American isthmus was raised, the region had been underwater. The islands of the West Indies delineate a submerged former land bridge, which had connected North America and South America via what are now Florida and Venezuela. Much of North America is on the North American Plate.
The continental coastline is long and irregular. The Gulf of Mexico is the largest body of water indenting the continent, followed by Hudson Bay. Others include the Gulf of Saint Lawrence and the Gulf of California.
There are numerous islands off the continent’s coasts: principally, the Arctic Archipelago, the Bahamas, Turks & Caicos, the Greater and Lesser Antilles, the Aleutian Islands, the Alexander Archipelago, the many thousand islands of the British Columbia Coast, Newfoundland and Greenland, a self-governing Danish island, and the world's largest, is on the same tectonic plate (the North American Plate) and is part of North America geographically. Bermuda is not part of the Americas, but is an oceanic island which was formed on the fissure of the Mid-Atlantic Ridge over 100 million years ago. The nearest landmass to it is Cape Hatteras, North Carolina, and it is often thought of as part of North America, especially given its historical, political and cultural ties to Virginia and other parts of the continent.