Congressional Apportionment Amendment
At the time it was sent to the states for ratification, an affirmative vote by ten states would have made this amendment operational. That number rose to eleven on March 4, 1791, when Vermont joined the Union. By the end of 1791, the amendment was only one state short of the mark. However, when Kentucky attained statehood on June 1, 1792, the number climbed to twelve, and, even though Kentucky ratified the amendment that summer (along with the other eleven amendments), it was still one state short. No additional states ratified this amendment since. To become part of the Constitution, 27 additional ratifications are required.