The United States Constitution received its final signatures on September 17, 1787, at Independence Hall in Philadelphia.
The signing concluded the Constitutional Convention, which had met for four months to replace the Articles of Confederation with a stronger federal framework. George Washington, presiding over the convention, signed first, followed by 38 other delegates. Rhode Island did not send delegates, and some convention attendees declined to sign.
Signing did not immediately make the Constitution operative. The document still required ratification by the states, and Article VII specified approval by nine states. New Hampshire supplied the decisive ninth ratification on June 21, 1788. The new federal government began operating under the Constitution on March 4, 1789, making September 17 a key milestone in the constitutional history celebrated around America250.