Delaware was the first state to ratify the U.S. Constitution, approving it on December 7, 1787.
Delaware’s constitutional convention met in Dover and ratified the document unanimously. All 30 delegates voted in favor, giving Delaware the nickname “The First State.” Its early ratification helped establish the required sequence for the new federal system.
The Constitution required ratification by conventions in nine states before it could take effect among those states. Delaware’s vote came shortly after the document was signed in Philadelphia on September 17, 1787, but before Pennsylvania and New Jersey completed their approvals.
A common mix-up is confusing the first state to ratify with the first state admitted to the Union. Delaware was one of the original 13 states; Vermont became the 14th state in 1791. Delaware’s distinction concerns ratification, not later admission.