Which state became the ninth to ratify the U.S. Constitution, making it effective?

New Hampshire became the ninth state to ratify the U.S. Constitution, making it effective under Article VII.

New Hampshire ratified the Constitution on June 21, 1788. Article VII specified that ratification by conventions in nine of the 13 states would be sufficient to establish the Constitution among the states that approved it. New Hampshire’s vote supplied that required ninth ratification.

The Constitution had been signed in Philadelphia on September 17, 1787, but signing did not put it into effect. Delaware was first to ratify, while Pennsylvania, New Jersey, Georgia, Connecticut, Massachusetts, Maryland, and South Carolina followed before New Hampshire. Virginia and New York ratified later in 1788.

Rhode Island was the last of the original 13 states to ratify, doing so in 1790. New Hampshire’s role is therefore different from Delaware’s first ratification and North Carolina’s later ratification. The new federal government began operating in 1789.