In the history commemorated by America250, on what date was the U.S. Constitution signed?

The U.S. Constitution was signed on September 17, 1787, in Philadelphia.

The signing took place at the Pennsylvania State House, now known as Independence Hall, after the Constitutional Convention spent four months debating a new framework of government. Thirty-nine delegates representing 12 states endorsed the document; Rhode Island did not send delegates to the convention.

George Washington, who chaired the convention, signed first. The Constitution then had to be ratified by the states before it could take effect. Delaware became the first state to ratify, while Rhode Island became the last of the original 13 states to do so.

The date is sometimes confused with June 21, 1788, when New Hampshire supplied the ninth ratification needed for the Constitution to become operational, or March 4, 1789, when the new federal government began functioning.