The U.S. Constitution was signed at Independence Hall in Philadelphia in 1787.
The signing took place on September 17, 1787, at the final session of the Constitutional Convention. Delegates had met in Philadelphia for nearly four months to design a stronger federal government after the weaknesses of the Articles of Confederation became apparent.
George Washington presided over the convention and signed first. Thirty-nine delegates ultimately signed the document, representing 12 states; Rhode Island did not send delegates. Three delegates who remained at the convention declined to sign: Edmund Randolph, George Mason, and Elbridge Gerry.
Signing the Constitution did not immediately make it effective. Article VII required ratification by nine states, which New Hampshire supplied on June 21, 1788. The new federal government began operating under the Constitution on March 4, 1789. The signing date is therefore distinct from both ratification and the Constitution’s effective date.