Delegates signed the United States Constitution at the Philadelphia Convention in 1787.
The Constitutional Convention met from May 25 to September 17, 1787, at the Pennsylvania State House in Philadelphia. The delegates had originally gathered to revise the Articles of Confederation, the first national governing framework of the United States. Instead, they designed an entirely new Constitution with a stronger federal government.
George Washington presided over the convention, while James Madison kept extensive notes and became a major architect of the document. Major compromises addressed representation in Congress, the relationship between large and small states, and the counting of enslaved people for representation and taxation. The convention approved the final text on September 17.
Thirty-nine delegates signed the Constitution on that date, although several delegates refused to sign and others had already departed. The document did not become operative immediately: Article Seven required ratification by nine states. The new federal government began under the Constitution in 1789, after the required states had approved it.