Delaware was the first state to ratify the U.S. Constitution, doing so on December 7, 1787.
The ratification convention in Delaware approved the Constitution unanimously, with all 30 delegates voting in favor. This earned Delaware the nickname “The First State,” which remains part of its official identity and state branding.
The Constitution required ratification by nine states before it could take effect. Delaware’s action came first, followed by Pennsylvania on December 12, 1787, and New Jersey on December 18. New Hampshire became the crucial ninth state on June 21, 1788, making the Constitution operative.
Delaware is sometimes confused with Virginia or Pennsylvania because those states played major roles in the Constitutional Convention and early national politics. However, neither ratified first. Rhode Island was the last of the original 13 states to approve the Constitution, on May 29, 1790.