The U.S. Constitution sets out many guidelines for the number of votes required to take certain actions. However, only one process requires a three-fourths majority vote: amending the Constitution itself. To change the Constitution, three-fourths of all states must ratify, or approve an amendment.

Two Ways to Ratify

Article V of the Constitution provides two ways that a state can ratify a proposed amendment. When the amendment is proposed, it specifies whether the amendment must be passed by three-fourths of the states' legislatures, or by three-fourths of a state convention. Historically, state legislatures have had the final say on whether an amendment will become part of the Constitution. State conventions have ratified only one amendment. The 21st Amendment, which repealed Prohibition, was ratified by three-fourths of the states in 1933. At the time of publication, ratification of a Constitutional amendment requires the approval of 38 states.