The last state to ratify the United States Constitution was Rhode Island, which did so on May 29, 1790. Rhode Island was initially reluctant, rejecting calls for a ratifying convention seven times and even defeating the Constitution in a plebiscite before finally ratifying it by a narrow vote of 34 to 32. This ratification came more than a year after the Constitution had gone into effect, making Rhode Island the 13th and final original state to join the Union under the new Constitution.
