Which original U.S. state was the last to ratify the Constitution?

Rhode Island was the last of the original U.S. states to ratify the Constitution.

Rhode Island ratified the Constitution on May 29, 1790, nearly three years after the Constitutional Convention sent the document to the states. It became the thirteenth state to ratify, completing the original group of states under Article Seven’s process.

The state had refused to send delegates to the 1787 Constitutional Convention and was especially wary of a stronger federal government. Many Rhode Islanders defended the authority of the state and opposed federal taxation and other powers they believed could threaten local independence. The state’s delay gave it the nickname “Rogue Island” in some contemporary discussions.

The Constitution had already taken effect after New Hampshire became the ninth state to ratify it on June 21, 1788. Rhode Island’s later decision therefore did not determine when the new government began operating, but it completed the original states’ formal ratification process. Its final vote followed pressure from the other states and assurances concerning individual rights.