The United States of America is a federal constitutional republic located in North America, comprising 50 states, a federal district (Washington, D.C.), and several territories. It is the third-largest country by total area and among the three most populous, with approximately 341 million people as of 2025.¹⁾ The country is bordered by Canada to the north, Mexico to the south, the Atlantic Ocean to the east, and the Pacific Ocean to the west.

The United States operates under a federal system established by the Constitution of 1787, ratified in 1788 and taking effect in 1789. The Constitution divides power between the federal government and the states. The federal government is organized into three branches: the legislative (a bicameral Congress consisting of the Senate and the House of Representatives), the executive (headed by the President), and the judicial (headed by the Supreme Court). Article I of the Constitution establishes Congress as the first and most extensively defined branch; the degree to which the three branches are functionally equal has been a matter of ongoing constitutional debate.

The first ten amendments to the Constitution, ratified in 1791 and collectively known as the Bill of Rights, enumerate specific protections for individual rights against federal government action. These include freedom of speech, the press, and religion (First Amendment); the right to keep and bear arms (Second Amendment); protections against unreasonable searches and seizures (Fourth Amendment); due process and protection against self-incrimination (Fifth Amendment); the right to a speedy trial (Sixth Amendment); and protection against cruel and unusual punishment (Eighth Amendment). The Ninth Amendment specifies that the enumeration of certain rights shall not be construed to deny others retained by the people, and the Tenth Amendment reserves to the states or the people all powers not delegated to the federal government. Subsequent amendments extended Bill of Rights protections against state governments as well as federal action, a process known as incorporation.

The United States uses a two-party system in practice, dominated by the Democratic and Republican parties, though this is not mandated by the Constitution.

The continental United States spans a vast and geographically diverse area from the Atlantic to the Pacific coast, encompassing arctic tundra (Alaska), tropical islands (Hawaii), arid deserts, temperate forests, plains, and mountain ranges. The population is highly diverse by national origin, religion, and ethnicity, reflecting centuries of immigration.

English is the dominant language of government and commerce. No federal statute designates an official language, though 32 of the 50 states have formally designated English as an official state language through statutes or constitutional amendments.²⁾ The 18 states without such a designation include California, Texas, New York, Florida, and Illinois — the five most populous states — meaning the 32 states with official English status represent roughly 55–60% of the total U.S. population. For further discussion of language policy at the state and federal level, see United States - Language Policy Viewpoints.

The territory now comprising the United States was inhabited by Indigenous peoples for thousands of years before European colonization beginning in the 16th and 17th centuries. Thirteen British colonies declared independence in 1776, established a republic, and expanded westward over the following century through purchase, treaty, and conquest. The country fought a devastating Civil War (1861–1865) over secession and slavery, industrialized rapidly in the late 19th century, and emerged from the Second World War as a global superpower. The ensuing Cold War placed the United States in sustained geopolitical competition with the Soviet Union until the latter's dissolution in 1991. See United States - History for a full treatment.

The United States has the largest nominal GDP in the world³⁾ and operates primarily as a market economy with significant government involvement in areas such as defense, social insurance, and regulation. Major sectors include technology, finance, healthcare, agriculture, manufacturing, and energy. The U.S. dollar serves as the world's primary reserve currency. The degree to which government should intervene in markets is a persistent and unresolved political debate — see United States - Economic Policy Viewpoints.

The United States maintains the world's largest military budget and an extensive global military presence through bases, alliances (including NATO), and bilateral agreements. Its foreign policy role — whether as global policeman, reluctant hegemon, or overreaching empire — is sharply contested. See United States - Foreign Policy Viewpoints.

American culture is pluralistic and regionally varied, shaped by its history of immigration, frontier expansion, religious diversity, and the tension between individual liberty and collective identity. It has produced influential contributions to music, film, literature, and technology that have spread globally. Social questions around race, religion, gender, and class remain active fault lines in American public life.

A number of significant controversies have their own pages on this wiki:

• The proper scope and interpretation of constitutional rights is one of the most contested areas of American law and politics — see United States - Constitutional Interpretation Viewpoints.
• Immigration policy — including legal immigration levels, enforcement, and citizenship — is a defining political flashpoint — see United States - Immigration Viewpoints.
• The history and legacy of race-based policies, from slavery to affirmative action and DEI, generates deep disagreement — see United States - Race and Policy Viewpoints.
• The United States' role in international institutions and alliances is contested across the political spectrum.
• The structure and financing of American healthcare is a major ongoing political dispute — see United States - Healthcare Viewpoints.

• United States - Conservative American Viewpoint
• United States - Modern Progressive American Viewpoint