North America is the third largest continent and has a population of approximately 528 million, as of July 2015. The three major North American countries are Canada, the United States and Mexico. The five major geographic regions are the mountainous west, Great Plains, Canadian Shield, Appalachian Mountains and East Coast.
North America is bounded on each side by oceans and seas, with one small strip of land connecting it to South America. The Appalachian Mountains in the east date from the collision of the North American tectonic plate with the European plate from approximately 480 to 230 million years ago. The Canadian Shield is the remnant of even earlier mountains. The Great Plains were once covered by shallow seas, and the collision of the North American plate into the Pacific plate creates the western mountains.
The first humans arrived in North America from Asia approximately 20,000 years ago. They traveled from the Alaska area down throughout the continent and into South America. The first European visitors to North America came from Scandinavia. Europeans started settling in North American in much greater numbers after Christopher Columbus rediscovered North America in 1492. The Americas are named after later explorer Amerigo Vespucci.
Most people in Canada and the United States descend from European immigrants, while Central America retains a far more indigenous heritage. Immigration to North America continues from around the world.