United States

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 a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States also asserts sovereignty over five major island territories and various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's third-largest land area and third-largest population, exceeding 341 million. Paleo-Indians first migrated from North Asia to North America at least 15,000 years ago, and formed various civilizations. Spanish colonization established Spanish Florida in 1513, the first European colony in what is now the continental United States. British colonization followed with the 1607 settlement of Virginia, the first of the Thirteen Colonies. Enslavement of Africans was practiced in every colony and supplied most of the labor for the Southern Colonies' plantation economy. Clashes with the British Crown began as a civil protest over the illegality of taxation without representation in Parliament and the denial of other English rights. They evolved into the American Revolution, which led to the Declaration of Independence and a society based on universal rights. Victory in the 1775–1783 Revolutionary War brought international recognition of U.S. sovereignty and fueled westward expansion, further dispossessing native inhabitants. As more states were admitted into the Union, a North–South division over slavery led 11 Southern states to attempt to secede and join as the Confederate States of America, which fought against the Union in the American Civil War of 1861–1865. With the United States' victory and reunification, slavery was abolished nationally. By 1900, the country had established itself as a great power, a status solidified after its involvement in World War I. Following Japan's attack on Pearl Harbor in 1941, the U.S. entered World War II. Its aftermath left the U.S. and the Soviet Union as rival superpowers, competing for ideological dominance and international influence during the Cold War. The collapse of the Soviet Union in 1991 ended the Cold War, leaving the U.S. as the world's sole superpower. After the terror attacks of September 11, 2001, the U.S. launched the war on terror, invading Afghanistan and Iraq. It has continued carrying out numerous foreign interventions since then. The U.S. federal government is a representative democracy with a president and a constitution that creates a separation of powers among three branches: legislative, executive, and judicial. The United States Congress is 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). Federalism grants substantial autonomy to the 50 states. In addition, 574 Native American tribes have sovereignty rights, and there are 326 Native American reservations. Since the 1850s, the Democratic and Republican parties have dominated American politics in a de facto two-party system. American ideals and values are based on a democratic tradition inspired by the American Enlightenment movement. A developed country, the U.S. ranks high in economic competitiveness, innovation, and higher education. Accounting for over a quarter of nominal global GDP, its economy has been the world's largest since about 1890. It is the wealthiest country, with the highest disposable household income per capita among OECD members, though its wealth inequality is highly pronounced. Shaped by centuries of immigration, the culture of the U.S. is diverse and globally influential. Making up more than a third of global military spending, the country is widely considered to have the most powerful armed forces in the world and was the first to develop nuclear weapons. A member of numerous international organizations including the United Nations Security Council, the U.S. plays a major role in global political, cultural, economic, and military affairs.