U.S. Inspection Station U.S. Custom House

The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and Washington, D.C., its federal capital district. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclavic state of Alaska in the northwest and the archipelagic state of Hawaii in the Pacific Ocean. Within the U.S. are 574 federally recognized tribal governments and 326 Indian reservations with tribal sovereignty rights. The U.S. asserts sovereignty over five major island territories and various uninhabited islands. It is a megadiverse country, with the world's third-largest land area and third-largest population, exceeding 340 million.

Paleo-Indians migrated to North America across the Bering land bridge more than 12,000 years ago, and formed various civilizations and societies. Spanish exploration and colonization led to the establishment in 1513 of Spanish Florida, the first European colony in what is now the continental United States. France also began to colonize at this time, but major settlements came much later. Subsequent British colonization led to the first settlement of the Thirteen Colonies in Virginia in 1607. Intensive agriculture in the rapidly expanding Southern Colonies encouraged the forced migration of enslaved Africans. Clashes with the British Crown over taxation and political representation sparked the American Revolution, with the Second Continental Congress formally declaring independence on July 4, 1776. Following its victory in the 1775–1783 Revolutionary War, the country continued to expand westward across North America, dispossessing Native Americans as it fought the Indian Wars. The 1803 purchase of Louisiana from Napoleonic France and the end of the Mexican–American War in 1848 provided vast territories for expansion. As more states were admitted, a North–South division over slavery led to the secession of the Confederate States of America, which fought the Union in the 1861–1865 American Civil War. With the victory and preservation of the United States, slavery was abolished nationally. By the late 19th century, the United States established itself as a great power with victory in the Spanish–American War, a status solidified with its participation in World War I. Following Japan's attack on Pearl Harbor in December 1941, the U.S. entered World War II; its aftermath left the U.S. and the Soviet Union as the world's superpowers. During the Cold War, both countries struggled for ideological dominance and international influence. The end of the Cold War and the Soviet Union's collapse in 1991 left the U.S. as the world's sole superpower.

The U.S. national government is a presidential constitutional federal republic and liberal democracy with three separate branches: legislative, executive, and judicial. It has a bicameral national legislature composed of the House of Representatives, a lower house based on population, and the Senate, an upper house based on equal representation for each state. The country's Democratic and Republican parties have dominated American politics since the 1850s. Federalism provides substantial autonomy to the 50 states, while American values are based on a political tradition that draws its inspiration from the European Enlightenment movement. A melting pot of many ethnicities and customs, the culture of the United States has been shaped by centuries of immigration, and its soft power influence has a global reach.

One of the world's most developed countries, the U.S. ranks among the highest in economic competitiveness, productivity, innovation, human rights, and higher education. The United States accounted for over a quarter of nominal global economic output in 2024, and its economy has been the world's largest by nominal GDP since about 1890. It possesses by far the largest amount of wealth of any country and has the highest disposable household income per capita among OECD countries, though U.S. wealth inequality is higher than in most other developed countries. The U.S. is a member of multiple international organizations and plays a leading role in global political, cultural, economic, and military affairs.

Etymology

Documented use of the phrase "United States of America" dates back to January 2, 1776. On that day, Stephen Moylan, a Continental Army aide to General George Washington, wrote a letter to Joseph Reed, Washington's aide-de-camp, seeking to go "with full and ample powers from the United States of America to Spain" to seek assistance in the Revolutionary War effort. The first known public usage is an anonymous essay published in the Williamsburg newspaper ''The Virginia Gazette'' on April 6, 1776. Sometime on or after June 11, 1776, Thomas Jefferson wrote "United States of America" in a rough draft of the Declaration of Independence, which was adopted by the Second Continental Congresson July 4, 1776. Davis 1996, p. 7.

The term "United States" and its initialism "U.S.", used as nouns or as adjectives in English, are common short names for the country. The initialism "USA", a noun, is also common. "United States" and "U.S." are the established terms throughout the U.S. federal government, with prescribed rules. "The States" is an established colloquial shortening of the name, used particularly from abroad; "stateside" is the corresponding adjective or adverb.

"America" is the feminine form of the first word of , the Latinized name of Italian explorer Amerigo Vespucci (1454–1512); it was first used as a place name by the German cartographers Martin Waldseemüller and Matthias Ringmann in 1507. Vespucci first proposed that the West Indies discovered by Christopher Columbus in 1492 were part of a previously unknown landmass and not among the Indies at the eastern limit of Asia. In English, the term "America" rarely refers to topics unrelated to the United States, despite the usage of "the Americas" to describe the totality of North and South America.

History

Indigenous peoples

The first inhabitants of North America migrated from Siberia over 12,000 years ago, either across the Bering land bridge or along the now-submerged Ice Age coastline. The Clovis culture, which appeared around 11,000 BC, is believed to be the first widespread culture in the Americas. Over time, indigenous North American cultures grew increasingly sophisticated, and some, such as the Mississippian culture, developed agriculture, architecture, and complex societies. In the post-archaic period, the Mississippian cultures were located in the midwestern, eastern, and southern regions, and the Algonquian in the Great Lakes region and along the Eastern Seaboard, while the Hohokam culture and Ancestral Puebloans inhabited the southwest. Native population estimates of what is now the United States before the arrival of European immigrants range from around 500,000 to nearly 10 million.

European exploration, colonization and conflict (1513–1765)

Christopher Columbus began exploring the Caribbean for Spain in 1492, leading to Spanish-speaking settlements and missions from Puerto Rico and Florida to New Mexico and California. The first Spanish colony in what is now the continental United States was Spanish Florida, chartered in 1513. After several settlements failed there due to hunger and disease, Spain's first permanent town, Saint Augustine, was founded in 1565. France established its own settlements in French Florida in 1562, but they were either abandoned (Charlesfort, 1578) or destroyed by Spanish raids (Fort Caroline, 1565); permanent French settlements would be founded much later along the Great Lakes (Fort Detroit, 1701), the Mississippi River (Saint Louis, 1764) and especially the Gulf of Mexico (New Orleans