The Constitutional Convention signed the U.S. Constitution on September 17, 1787, a later milestone in America’s 250-year story.
Delegates met in Philadelphia to revise the Articles of Confederation, but they ultimately designed an entirely new framework for the federal government. The Constitution established three branches, defined federal powers, and created a system of checks and balances.
Thirty-nine delegates signed the completed document on September 17. The Constitution did not take effect immediately; it required ratification by the states. New Hampshire became the ninth state to ratify it on June 21, 1788, allowing the Constitution to take effect, and the new federal government began operating in 1789.
September 17 is now observed in the United States as Constitution Day and Citizenship Day. It is distinct from July 4, the date associated with the Declaration of Independence and the central anniversary commemorated by America250.