North America covers an area of about 24,709,000 square kilometers (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 across 23 independent states, representing about 7.5% of the human population. North America is the third-largest continent in area, following Asia and Africa, and the fourth in population after Asia, Africa, and Europe.
The first people to live in North America were Paleoindians who began to arrive during the last glacial period by crossing the Bering land bridge. They differentiated into a number of diverse cultures and communities across the continent. The largest and most advanced Pre-Columbian civilizations in North America were the Aztecs in what is now Mexico and the Mayans in Central America. European colonists began to arrive starting in the 16th and 17th centuries, wiping out large numbers of the native populations and beginning an era of European dominance.