The United States Constitution was signed in 1787, a milestone highlighted by America250 history.
Delegates to the Constitutional Convention signed the document on September 17, 1787, at the Pennsylvania State House in Philadelphia, now known as Independence Hall. The convention had met to address weaknesses in the government created by the Articles of Confederation.
The Constitution established the framework of the federal government, including its legislative, executive, and judicial branches. It did not take effect immediately upon signing: ratification by the states was required, and the new government began operating in 1789.
The year 1788 is a common mix-up because New Hampshire’s ratification that year supplied the ninth state needed for the Constitution to take effect. The Bill of Rights was added later, in 1791, as the first ten amendments.