New Hampshire ratified the U.S. Constitution as the ninth state on June 21, 1788, meeting Article VII’s requirement for the new framework to take effect.
Article VII specified that conventions in nine of the thirteen states had to ratify the Constitution before it could become operative among the ratifying states. New Hampshire’s convention reached that threshold after eight states had already approved the document.
The vote was 57–47, making New Hampshire’s decision considerably closer than Delaware’s unanimous 30–0 ratification. Virginia ratified four days later, and New York followed on July 26, 1788. Those later approvals strengthened the new union politically, even though the constitutional threshold had already been met.
Ratification continued after the federal government began operating under the Constitution. North Carolina approved it in November 1789, and Rhode Island became the thirteenth and final original state to ratify on May 29, 1790. The ninth-state rule is therefore distinct from the date on which every original state had joined the constitutional system.