Answer: Delaware, Pennsylvania, and New Jersey
All three of those states ratified the US Constitution in December, 1787. Delaware's state legislature was first to ratify, on Dec. 7. Pennsylvania's legislature ratified on Dec. 12, and New Jersey on Dec. 18. In Delaware and New Jersey, the vote in each state legislature was unanimous in support of ratification of the Constitution. In Pennsylvania, the state legislature voted 46 to 23 in favor of ratification.
Support for ratification followed closely in Georgia and Connecticut. Georgia's legislature voted unanimously for ratification on January 2, 1788. Connecticut's legislature voted 128 to 40 in favor of ratification on January 9.
By the spring of 1788, the required 9 of 13 states had ratified the Constitution. Ultimately, all 13 state legislatures did vote in favor of ratification, though the margin was close in some states.