The Constitution of the United States

The Constitution was signed by 39 delegates in Philadelphia on September 17, 1787, ratified when New Hampshire became the ninth state to approve it on June 21, 1788, and took effect on March 4, 1789. It replaced the Articles of Confederation, under which the national government could not tax, regulate commerce, or enforce its laws. At about 4,400 words in its original form, it is the oldest written national constitution still in use. The signed original is displayed in the Rotunda of the National Archives.

Its structure follows the separation of powers. Article I creates Congress, Article II the presidency, and Article III the federal judiciary. Article IV governs relations among the states, including full faith and credit, privileges and immunities, extradition, admission of new states, and a guarantee of republican government. Article V sets the amendment process, Article VI makes the Constitution and federal law supreme and bars religious tests for office, and Article VII provided for ratification.

The Constitution has been amended 27 times. The first ten, the Bill of Rights, were ratified in 1791. The Civil War amendments, the Thirteenth, Fourteenth, and Fifteenth, abolished slavery and guaranteed citizenship, due process, equal protection, and voting rights regardless of race. Others changed how government works, providing for an income tax, the direct election of senators, presidential term limits, and succession. The Twenty-seventh, delaying congressional pay raises, was proposed in 1789 and ratified in 1992.

Amendments require two thirds of both houses of Congress to propose, or a convention called by two thirds of the states, which has never happened, and ratification by three quarters of the states. The bar is among the highest in the world, so most constitutional change has come through interpretation by the courts and practice by the political branches. Each section of the document is covered on its own page on this site, along with the cases that define its meaning today.