Stretching from the Atlantic to the Pacific and encompassing more than 3.79 million square miles, the United States of America has a remarkable diversity of landscapes and climates, including the Southern swamps and Everglades, the immense Great Lakes, the soaring Rocky Mountains, the windswept Great Plains, the arid deserts of the Southwest and over 12,000 miles of coastline. More than 10,000 years before Christopher Columbus landed in the Bahamas in 1492, ushering in an era of European colonization of the New World, the nomadic ancestors of modern Native Americans began settling across the North American continent. In the 16th, 17th and 18th centuries, immigrants who came to America seeking economic opportunity or religious freedom struggled to build thriving communities in the uncharted wilderness, often to the detriment of indigenous peoples. By the 1770s, some 2.5 million European colonists had settled in America. In 1776, those living in Great Britain’s 13 colonies declared their independence, sparking the Revolutionary War and transforming the United States of America into an autonomous nation. During the 19th and 20th centuries, 37 new states were added as the country expanded from coast to coast and beyond, even as internal conflicts such as the Civil War and the fight for equal rights for all citizens threatened to divide the population. In the 20th century the United States played a major role in both world wars and emerged as a leading global power. Today it boasts the largest economy on the planet and is home to 310 million people; California, Texas and New York are its most populous states.