When was the United States Constitution signed at Philadelphia’s Independence Hall?

The United States Constitution was signed on September 17, 1787, at Independence Hall in Philadelphia.

The signing concluded the Constitutional Convention, which had met from May 25 through September 17 to replace the Articles of Confederation with a stronger federal framework. Delegates approved a document containing a preamble, seven articles, and a closing endorsement.

Thirty-nine delegates signed the Constitution, representing 12 states. Rhode Island had declined to send delegates, and three delegates present—George Mason, Edmund Randolph, and Elbridge Gerry—refused to sign. George Washington, who presided over the convention, signed first.

Signing did not immediately make the Constitution effective. Article VII required ratification by nine states, which occurred when New Hampshire ratified it on June 21, 1788. The new federal government began operating under the Constitution on March 4, 1789, so the signing, ratification, and effective dates are separate milestones.