Delaware was the first state to ratify the U.S. Constitution, doing so on December 7, 1787.
Article Seven required nine of the 13 states to ratify the Constitution before it could take effect. State conventions, rather than ordinary legislative votes, considered the document. Delaware’s convention approved it unanimously, 30–0, making Delaware the first state to act.
Pennsylvania followed on December 12, 1787, and New Jersey ratified six days later. New Hampshire became the ninth state to approve the Constitution on June 21, 1788, placing the new federal government on a constitutional footing.
Delaware’s first-place ratification is why it is commonly known as “The First State.” This title refers specifically to ratifying the Constitution, not to declaring independence or becoming the earliest European colony. Rhode Island was the last of the original 13 states to ratify, on May 29, 1790.