On what date did representatives sign the United States Constitution at Independence Hall?

Representatives signed the United States Constitution on September 17, 1787, at Independence Hall in Philadelphia.

The signing concluded the Constitutional Convention, which had met during the summer of 1787 to revise the Articles of Confederation. Instead of simply amending the existing system, the delegates produced an entirely new framework for the federal government.

Thirty-nine delegates signed the document. They represented 12 states; Rhode Island had declined to send delegates to the convention. George Washington, who presided over the convention, signed first, followed by the other delegates.

Signing did not immediately make the Constitution effective. The document required ratification by conventions in at least nine states. New Hampshire became the ninth state to ratify it on June 21, 1788, and the new federal government began operating in 1789. Constitution Day in the United States is observed each year on September 17.