State ratifying conventions are one of the two methods and ratifying conventions have only been used on one occasion, that being for the ratification of the Constitution's 21st Amendment so the 21st Amendment is the only constitutional amendment that was ratified by approval of conventions in three-fourths of the states.
The 21st Amendment is unique as it is the only amendment ratified by conventions in three-fourths of the states, repealing Prohibition. This process was initiated to prevent conservative state legislatures from blocking the repeal. Ratified on December 5, 1933, it highlights the significant role of state conventions in the constitutional amendment process.
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