Thirty-nine delegates signed the U.S. Constitution at Philadelphia’s Constitutional Convention on September 17, 1787.
The convention began with a broader group of appointed delegates, but 55 ultimately attended at least part of its proceedings. Three delegates who remained until the end—George Mason, Edmund Randolph, and Elbridge Gerry—refused to sign. Other delegates had already left Philadelphia.
The Constitution was signed at Independence Hall, then known as the Pennsylvania State House. George Washington, who presided over the convention, signed first. The signers represented 12 states; Rhode Island had declined to send delegates to the convention.
The number 39 is often confused with 55, the number of delegates who attended at some point. It is also distinct from the 74 people originally selected by the states. Benjamin Franklin, at age 81, was the oldest signer, while Jonathan Dayton, age 26, was the youngest.