Thirty-nine delegates signed the United States Constitution at Independence Hall on September 17, 1787.
The Constitutional Convention included 55 delegates at different points, but not all remained through the final signing. Some delegates had left Philadelphia, while others refused to endorse the finished document. The 39 signers represented 12 states because Rhode Island had not participated in the convention.
George Washington signed first as convention president. The delegates then signed by state, with the names arranged in a progression from northern to southern states. The convention secretary, William Jackson, also signed to authenticate corrections, but he was not counted among the 39 delegates.
The number of signers is sometimes confused with the convention’s total attendance or with the 38 delegates who followed Washington’s signature. Benjamin Franklin, aged 81, was the oldest signer, while Jonathan Dayton, aged 26, was the youngest. The Constitution later required state ratification before taking effect.