Delaware was the first state to ratify the U.S. Constitution, doing so on December 7, 1787.
Delaware’s ratifying convention met in Dover, and its delegates approved the Constitution unanimously, by a vote of 30–0. This earned Delaware the nickname “The First State,” which remains part of its official identity.
Article Seven required nine states to ratify the Constitution before it could take effect. New Hampshire became the crucial ninth state on June 21, 1788, while Delaware acted nearly seven months earlier. The Constitution therefore became binding before every state had approved it.
Delaware is sometimes confused with Pennsylvania or New Jersey because both were among the first states to ratify. Pennsylvania ratified second on December 12, 1787, and New Jersey followed third on December 18. Rhode Island was the last original state to ratify, in 1790.