Delaware became the first state to ratify the United States Constitution in 1787.
Delaware's constitutional convention approved ratification unanimously on December 7, 1787. The vote took place at Dover, making Delaware the first of the thirteen states to accept the proposed federal framework.
The state later gained the nickname “The First State” because of this sequence. Its delegates had participated in the Constitutional Convention in Philadelphia, where the new Constitution was drafted and signed earlier in 1787.
Delaware's early ratification did not make the Constitution effective by itself. The document required approval by nine states, and that threshold was reached when New Hampshire ratified it on June 21, 1788. A common mix-up is treating Delaware's first ratification as the Constitution's signing date; signing and state approval were separate steps in the creation of the new government.