The United States of America (USA or U.S.A.), commonly known as the United States (US or U.S.) or America, is a country primarily located in North America, between Canada and Mexico. It is a liberal democracy and republic of 50 federated states, a federal capital district (Washington, D.C.), and 326 Indian reservations that overlap with state boundaries. Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands.[i] The country has the world's third-largest land area,[c] largest maritime exclusive economic zone, and the third-largest population (over 334 million).[j] The federal government uses a presidential system with three separate branches: legislative, executive, and judicial.
American territory was first settled by Paleo-Indians who migrated across the Bering land bridge over 12,000 years ago. Colonization by the British began in 1607. Thirteen colonies eventually rebelled against the British Crown over taxation and political representation, declaring independence on July 4, 1776. Their victory in the American Revolutionary War (1775–83) resulted in a confederation of states before the U.S. Constitution and Bill of Rights were ratified. The young nation continued to acquire neighboring territories and spanned North America by the late 1840s. Longstanding disagreements over slavery led to the secession of the southern Confederate States of America, which were defeated by the remaining Union in the American Civil War (1861–65). Slavery was abolished, but discriminatory laws persisted in the South. By 1900, rapid industrialization established the United States as a great power and the world's largest economy. Following the Japanese attack on Pearl Harbor in December 1941, the United States joined the Allies of World War II. After their victory, it competed against the Soviet Union for dominance in nuclear and conventional weaponry, ideology, and international influence during the Space Race and Cold War. Many racist practices in the country were overturned in the 1960s, and U.S. astronauts became the first humans to land on the Moon (1969). The nation emerged as the world's sole superpower after the dissolution of the Soviet Union (1991).
The United States accounts for about 25% of the global economy and 30% of global wealth. It has the world's largest nominal GDP and ranks high in measures of income, wealth, economic competitiveness, productivity, innovation, human rights, and higher education. The country is home to globally important industries in aerospace and defense, automobiles, energy, entertainment, finance, healthcare, and information technology. The United States is a founding member of the United Nations (UN), the North Atlantic Treaty Organization, the Organization of American States, the International Monetary Fund, the World Bank, the World Trade Organization, and is a permanent member of the UN Security Council.
The first documentary evidence of the phrase "United States of America" dates back to a letter from January 2, 1776, written by Stephen Moylan, a Continental Army aide to General George Washington, to Joseph Reed, Washington's aide-de-camp. Moylan expressed his desire to go "with full and ample powers from the United States of America to Spain" to seek assistance in the Revolutionary War effort.[20][21] The first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, on April 6, 1776.[22]
By June 1776, the name "United States of America" appeared in drafts of the Articles of Confederation and Perpetual Union, authored by John Dickinson, a Founding Father from the Province of Pennsylvania, and in the Declaration of Independence, written primarily by Thomas Jefferson and adopted by the Second Continental Congress in Philadelphia, on July 4, 1776.[25]
