The Constitution of the United States is the supreme law of the United States. It superseded the Articles of Confederation, the nation's first constitution, on March 4, 1789. Originally including seven articles, the Constitution delineates the national frame and constrains the powers of the federal government. The Constitution's first three articles embody the doctrine of the separation of powers, in which the federal government is divided into three branches: the legislative, consisting of the bicameral Congress ; the executive, consisting of the president and subordinate officers ; and the judicial, consisting of the Supreme Court and other federal courts. Article IV, Article V, and Article VI embody concepts of federalism, describing the rights and responsibilities of state governments, the states in relationship to the federal government, and the shared process of constitutional amendment. Article VII establishes the procedure subsequently used by the 13 states to ratify it. The Constitution of the United States is the oldest and longest-standing written and codified national constitution in force in the world.

The United States of America, commonly known as the United States or America, is a country primarily located in North America. It is a federation of 50 states, a federal capital district, and 326 Indian reservations. Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands. The country has the world's third-largest land area, second-largest exclusive economic zone, and third-largest population, exceeding 334 million.