Delaware was the first state to ratify the U.S. Constitution, doing so on December 7, 1787.
Article Seven provided that the Constitution would take effect after nine states ratified it. Delaware's convention approved the document unanimously, making it the first of the thirteen states to accept the new federal framework.
Pennsylvania ratified five days later, followed by New Jersey and Georgia. New Hampshire became the ninth state to ratify in June 1788, which placed the Constitution into effect. Rhode Island was the last of the original thirteen states to ratify, in 1790.
Delaware's first-place status is sometimes confused with its later nickname, “The First State,” which refers to this constitutional ratification. The event belongs to the post-independence nation-building story that follows the Revolutionary era commemorated by America250.