Nine states had to ratify the United States Constitution before it took effect, a number central to America250 history.
Article VII of the Constitution specified that ratification by conventions in nine states would be sufficient to establish the Constitution among the states approving it. This threshold was two-thirds of the original thirteen states, rather than unanimous approval.
New Hampshire became the ninth ratifying state on June 21, 1788. The decision allowed the new federal government to proceed, although several important states had not yet ratified. Virginia approved the Constitution four days earlier, and New York followed in July.
The process continued after the Constitution took effect. North Carolina ratified in November 1789, and Rhode Island became the thirteenth and final original state to ratify in May 1790. The nine-state rule is therefore different from the later constitutional amendment process, which requires approval by three-fourths of the states.