The Constitutional Convention took place in Philadelphia from May 25 to September 17, 1787. Although the convention was intended to revise the league of states and first system of government under the Articles of Confederation, the intention from the outset of many of its proponents, chief among them James Madison of Virginia and Alexander Hamilton of New York, was to create a new frame of government rather than fix the existing one. The delegates elected George Washington of Virginia, former commanding general of the Continental Army in the late American Revolutionary War (1775–1783) and proponent of a stronger national government, to become President of the convention. The result of the convention was the creation of the Constitution of the United States, placing the Convention among the most significant events in American history.

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 It superseded the Articles of Confederation, the nation's first constitution, on March 4, 1789.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.