The framers knew their document would need to change. Under the Articles of Confederation, any amendment required the consent of every state, and a single state could block reform. Article V lowered that bar but kept it high, requiring broad agreement across Congress and the states. The result is one of the hardest constitutions in the world to amend.
This guide explains each path in Article V, walks through ratification and certification, reviews the amendments that passed and those that failed, and explains how constitutional meaning changes without amendment.
Article V provides two ways to propose amendments and two ways to ratify them. It also contains limits: until 1808 no amendment could affect the slave trade clauses, and no state may be deprived of its equal vote in the Senate without its consent. James Madison defended the design in Federalist No. 43 as guarding equally against excessive ease and excessive difficulty in changing the Constitution.
Much of how the Constitution works today comes from interpretation rather than amendment, beginning with judicial review in Marbury v. Madison. Courts have read broad phrases such as due process and commerce among the several states in ways that expanded or limited government power over time, and they sometimes overrule their own precedents. Originalists argue that changes of this kind should come through Article V, while supporters of a living Constitution argue that interpretation must adapt because formal amendment is so difficult.
The 27 amendments fall into a few waves: the Bill of Rights in 1791, two early structural fixes in 1795 and 1804, three Reconstruction amendments abolishing slavery and guaranteeing citizenship, equal protection, and voting rights regardless of race, a Progressive Era wave from 1913 to 1920 creating the income tax, direct election of senators, Prohibition, and women's suffrage, and twentieth-century changes to presidential terms, succession, and voting. The Twenty-sixth, lowering the voting age to 18, was ratified in about 100 days in 1971, while the Twenty-seventh took 202 years.
Six amendments were sent to the states but not ratified, including one on the size of the House in 1789, the Corwin Amendment of 1861 that would have shielded slavery, a child labor amendment in 1924, the Equal Rights Amendment in 1972, and a 1978 amendment giving the District of Columbia voting representation. The Equal Rights Amendment reached 38 ratifications only after its deadline had passed, and in January 2025 the outgoing President said he considered it ratified, though the Archivist has not certified it. Popular proposals that never cleared Congress include abolishing the Electoral College, congressional term limits, a balanced budget requirement, and overturning campaign finance rulings.
Congress proposes amendments by joint resolution passed by two thirds of the members present and voting in each chamber. The President does not sign or veto it, a rule the Supreme Court recognized as early as 1798. The second path, a national convention called on the application of two thirds of state legislatures, now 34 states, has never been used, though campaigns for a convention on a balanced budget, term limits, and other subjects have gathered many applications and raise unsettled questions about how such a convention would work.
Congress chooses whether states ratify through their legislatures or through special conventions. Every amendment except the Twenty-first, which repealed Prohibition in 1933, was ratified by legislatures. Ratification by 38 of the 50 states is required. Since the Eighteenth Amendment, Congress has often set a seven-year deadline. When enough states ratify, the Archivist of the United States certifies the amendment and publishes it in the Federal Register.
See what the amendments say in all 27 amendments, explained, read the original text in the Constitution, article by article, or learn how courts interpret it in judicial philosophies explained.