Article VII required ratification by nine states for the United States Constitution to take effect.
The Constitutional Convention submitted the proposed Constitution to state conventions rather than to the existing state legislatures. Article VII stated that approval by conventions in nine states would establish the Constitution among the states ratifying it. This was a major departure from the Articles of Confederation, which required unanimous state approval for important changes.
New Hampshire became the ninth state to ratify on June 21, 1788, putting the Constitution into operation. Virginia and New York followed soon afterward, strengthening the new union politically and geographically. North Carolina and Rhode Island initially remained outside the constitutional system, but both later ratified.
The nine-state rule is often confused with the final count of original states. All 13 original states eventually ratified, but unanimity was not required to launch the new federal government. Rhode Island, the last, approved the Constitution on May 29, 1790.