Delegates signed the U.S. Constitution on September 17, 1787, at Independence Hall, a later milestone in the national history highlighted by America250.
The Constitutional Convention had met in Philadelphia for four months to replace the Articles of Confederation with a stronger federal framework. Thirty-nine delegates endorsed the final document on September 17.
Twelve states were represented at the signing because Rhode Island declined to send delegates. The Constitution then required ratification by the states before it could take effect.
The signing date is sometimes confused with the Constitution’s effective date or with the date of the first presidential inauguration. The document became operative in 1789, and George Washington was inaugurated on April 30 of that year.