Rhode Island was the last of the original 13 states to ratify the U.S. Constitution.
Rhode Island ratified the Constitution on May 29, 1790, by a convention vote of 34 to 32. Its decision came nearly three years after the Constitution was signed in Philadelphia. The state had rejected a proposed ratifying convention in 1788 and held strong opposition to expanding federal power.
The Constitution became operative after New Hampshire became the ninth state to ratify it in June 1788. North Carolina and Rhode Island initially remained outside the new constitutional system, although both later joined it. Rhode Island’s delayed ratification reflected concerns about paper money, debt, individual rights, and the balance between state and federal authority.
Rhode Island was not the final state admitted to the Union; that is a different question involving later states. It was also not the final original state to approve every later constitutional amendment. Its distinction is specifically being the thirteenth and last of the original states to ratify the Constitution.