The Signing of the United States Constitution occurred on September 17, 1787, at Independence Hall in Philadelphia, Pennsylvania, when 39 delegates to the Constitutional Convention, representing 12 states, endorsed the Constitution created during the four-month-long convention. In addition to signatures, this endorsement, the Constitution's closing protocol, included a brief declaration that the delegates' work has been successfully completed and that those whose signatures appear on it subscribe to the final document. Included are, a statement pronouncing the document's adoption by the states present, a formulaic dating of its adoption, along with the signatures of those endorsing it. Additionally, the convention's secretary, William Jackson, added a note to verify four amendments made by hand to the final document, and signed the note to authenticate its validity.

Independence Hall is a historic civic building in Philadelphia, where both the United States Declaration of Independence and the United States Constitution were debated and adopted by America's Founding Fathers. The structure forms the centerpiece of the Independence National Historical Park and was designated a World Heritage Site in 1979.