The ratification of the conventions of nine states, shall be sufficient for the establishment of this Constitution between the states so ratifying the same.
What does it mean?
Article VII declares that the Constitution becomes law of the United States when it is ratified by nine states. Ratification proceedings took place in special state conventions specifically designed for this purpose. Delaware was the first state to ratify the Constitution on December 7, 1787. Although a couple of states (such as Rhode Island) planned to their ratification, the Constitution became law when New Hampshire ratified it on June 21, 1788.