Delegates signed the U.S. Constitution on September 17, 1787, a founding milestone remembered during America250.
The signing occurred at the Pennsylvania State House in Philadelphia, later known as Independence Hall, at the final session of the Constitutional Convention. Thirty-nine delegates endorsed the document, representing twelve states; Rhode Island had declined to send delegates.
The Constitution then entered the ratification process. Article VII required approval from nine states, and New Hampshire became the ninth to ratify on June 21, 1788. The new federal government began operating under the Constitution on March 4, 1789.
Signing was not the same as ratification. The delegates created and endorsed the document in September 1787, but the states had to approve it before it could become the nation’s governing framework. Three convention delegates refused to sign, including George Mason, Edmund Randolph, and Elbridge Gerry.