Which of the original states was the last to join the Union?

Rhode Island was the last of the original thirteen states to join the Union. Although it was one of the first colonies to declare independence from British rule and played an active role in the American Revolution, Rhode Island was hesitant to ratify the U.S. Constitution. The state only agreed to join the Union on May 29, 1790, after being the last of the original states to do so. This delay was largely due to concerns about the potential for federal overreach and a desire to maintain a strong level of state autonomy. Each of the other original states joined the Union before Rhode Island, highlighting its unique position among them during the formative years of the United States.