Thirty-nine delegates signed the United States Constitution in 1787.
The signing took place on September 17, 1787, at Independence Hall in Philadelphia, where the Constitutional Convention had met for four months. The delegates endorsed the completed document before the convention adjourned.
Delegates from 12 states signed; Rhode Island declined to send delegates to the convention. George Washington, who chaired the convention, signed alongside representatives including James Madison, Benjamin Franklin, and Alexander Hamilton.
The 39 signers were not every delegate who attended the convention. Some delegates had left Philadelphia before the final signing, and three present delegates—George Mason, Edmund Randolph, and Elbridge Gerry—refused to sign. The Constitution then required ratification by the states before taking effect.