North America million, though Cuba, Dominican Republic, Haiti, Puerto Rico (a territory of the United States), Jamaica, and Trinidad and Tobago each have populations higher than a million. Greenland has a small population of 55,984 for its massive size (2,166,000 km² or 836,300 mi²), and therefore, it has the world's lowest population density at 0.026 pop./km² (0.067 pop./mi²). While the United States, Canada, and Mexico maintain the largest populations, large city populations are not restricted to those nations. There are also large cities in the Caribbean. The largest cities in North America, by far, are Mexico City and New York. These cities
North America 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 579 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