North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere; it is also considered by some to be a northern subcontinent of the Americas . It is bordered to the north by the Arctic Ocean , to the east by the Atlantic Ocean , to the west and south by the Pacific Ocean , and to the southeast by South America and the Caribbean Sea .
North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), about 16.5% of the earth 's land area and about 4.8% of its total surface. North America is the third largest continent by area , following Asia and Africa , and the fourth by population after Asia , Africa , and Europe . In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7.5% of the world 's population , if nearby islands (most notably the Caribbean ) are included.
North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge approximately 40,000 to 17,000 years ago. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago (the beginning of the Archaic or Meso-Indian period). The Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended in 1492, and the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present- day cultural and ethnic patterns reflect different kinds of interactions between European colonists, indigenous peoples, African slaves and their descendants .