North America is a Continent in the northern hemisphere and mostly in the western hemisphere. 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 by area, following Asia and Africa and the fourth by population after Asia, Africa, and Europe.