The history of the United States as covered in schools and universities typically begins with either 1492 and Columbus, or—especially in recent years—with the prehistory of the Native peoples. Officially the United States of America began as an independent nation with the Declaration of Independence in July 1776. European colonists reached the Gulf and Pacific coasts, but the largest settlements were by the English on the East Coast, starting in 1607. By the 1770s the Thirteen Colonies contained two and half million people. They were prosperous, and had developed their own political and legal systems. The British government's threat to American self-government led to war in 1775 and the Declaration of Independence in 1776. With major military and financial support from France, the patriots won the American Revolution. In 1789 the Constitution became the basis for the United States federal government, with war hero George Washington as the first president. The young nation continued to struggle with the scope of central government and with European influence, creating the first political parties in the 1790s, and fighting a second war for independence in 1812.

The United States of America (commonly abbreviated to the United States, the U.S., the USA, America, and the States) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to the east and Russia to the west, across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories in the Pacific and Caribbean.

At 3.79 million square miles (9.83 million km²) and with over 312 million people, the United States is the third or fourth largest country by total area, and the third largest by both land area and population. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the world's largest national economy, with an estimated 2011 GDP of $15.1 trillion (22% of nominal global GDP and over 19% of global GDP at purchasing-power parity). Per capita income is the world's sixth-highest.