Thirty-nine delegates signed the Constitution of the United States, a founding document remembered during America250.
The signing occurred on September 17, 1787, at the Pennsylvania State House in Philadelphia, now known as Independence Hall. The delegates represented 12 states because Rhode Island declined to send representatives to the Constitutional Convention. George Washington, who presided over the convention, signed first.
The convention had included more delegates than the final group of signers. Some delegates had already departed, while others refused to endorse the finished document. Three delegates—George Mason, Edmund Randolph, and Elbridge Gerry—attended the convention but did not sign.
The Constitution was not immediately the operating government. It required ratification by nine states under Article VII, and the new federal government began operating in 1789. This makes the 1787 signing distinct from both the 1776 Declaration and the 2026 America250 anniversary.