The United States Constitution was signed on September 17, 1787, at Independence Hall in Philadelphia.
The signing concluded the Constitutional Convention, which had met for four months to revise the Articles of Confederation but ultimately produced an entirely new framework of government. Thirty-nine delegates from twelve states signed the final document; Rhode Island had declined to send delegates.
George Washington, who presided over the convention, signed first. Three delegates who attended the convention—Edmund Randolph, George Mason, and Elbridge Gerry—refused to sign. The convention secretary, William Jackson, also signed to authenticate corrections, but he was not a delegate.
Signing did not immediately make the Constitution operational across the country. Article Seven required ratification by nine states, which New Hampshire supplied on June 21, 1788. The new federal government began operating in 1789, after the Constitution had been ratified by the states.