The United States of America (U.S.A.) is a federal republic and a sovereign country primarily located in North America, consisting of 50 states and the federal capital district, Washington, D.C.. The concept of the "United States of America" was officially adopted by the Second Continental Congress on September 9, 1776, replacing the term "United Colonies," following the Declaration of Independence on July 4, 1776. The nation was formed after the American Revolution (1775–1783) to solve the problem of governance under the British monarchy, establishing an independent government.
The U.S. government operates under the Constitution of the United States, which was written in 1787 and became operational in 1789. This document establishes a system of checks and balances among three separate branches of government. Article I vests legislative power in the Congress, which is bicameral, consisting of the Senate and the House of Representatives. Article II establishes the executive branch, headed by the President, who serves as the head of state and government. Article III vests judicial power in the Supreme Court and lower federal courts. The first ten amendments, known as the Bill of Rights (adopted in 1791), guarantee fundamental rights, such as freedom of speech in Amendment I and due process in Amendment V.
The U.S. Constitution is the world's longest surviving written charter of government and is connected to the concept of federalism, where power is divided between the federal government and the states, as outlined in Article IV. The Constitution has been amended 27 times, most recently in 1992. Recent legislative changes include the One, Big, Beautiful Bill Act (Public Law 119-21), signed on July 4, 2025, which significantly affected federal taxes and created Trump Accounts for eligible children. Other recent developments include a comprehensive overhaul of the Federal Acquisition Regulation (FAR) and new executive orders, such as EO 14398, requiring federal agencies to insert diversity, equity, and inclusion (DEI)-related clauses into contracts.