For America250, nine states were required to ratify the Constitution before it could take effect among the ratifying states.
Article Seven stated that ratification by conventions in nine states would be sufficient to establish the Constitution between those states. This was a major change from the Articles of Confederation, which generally required unanimous state approval for important alterations.
New Hampshire became the ninth state to ratify on June 21, 1788. That vote supplied the constitutional threshold, even though Virginia and New York—two highly influential states—ratified afterward. North Carolina and Rhode Island joined later, completing the original thirteen-state group.
The nine-state rule did not mean the Constitution instantly erased all existing arrangements everywhere. It provided the legal basis for the new government among the states that accepted it, while political leaders continued working to bring the remaining states into the Union. The provision is found in Article Seven rather than in the amendments.