Delaware was the first state to ratify the U.S. Constitution, doing so on December 7, 1787.
The ratification took place at Dover, where Delaware’s convention approved the Constitution unanimously. This earned Delaware the nickname “The First State,” a title officially adopted by the state in 2002.
Delaware’s early approval helped establish momentum for the new federal framework. Pennsylvania became the second state to ratify, followed by New Jersey. The Constitution required approval from nine states before it could take effect, a threshold reached in June 1788 when New Hampshire ratified.
A common mix-up is confusing the first state to ratify with the first state admitted to the Union after the original thirteen. That state was Vermont, admitted in 1791. Delaware was one of the original thirteen states and was the first to approve the Constitution.