New Hampshire was the ninth state to ratify the United States Constitution, making it effective on June 21, 1788.
Article Seven specified that conventions in nine states had to approve the Constitution before it could take effect among the ratifying states. New Hampshire’s convention initially postponed a decision, then reconvened and approved the document by a vote of 57 to 47.
The ninth ratification was a crucial threshold, but it did not mean every state had accepted the Constitution. Virginia and New York ratified soon afterward, while North Carolina and Rhode Island remained outside the new constitutional system for longer. Rhode Island was the last of the original 13 states to ratify, in 1790.
The Constitution’s supporters often called the New Hampshire vote decisive because it supplied the required number. Delaware, by contrast, was the first state to ratify, and those two milestones are frequently confused when recalling the ratification sequence.