Question: has there ever been a convention of states

Answer: No, To become part of the Constitution, an amendment must be ratified by either--as determined by Congress--the legislatures of three-fourths (presently 38) of the states or State ratifying conventions in three-fourths of the states. Thirty-three amendments to the United States Constitution have been approved by Congress and sent to the states for ratification. Twenty-seven of these amendments have been ratified and are now part of the Constitution. As of 2018, the convention process has never been used for proposing constitutional amendments.