The U.S. Constitution has been formally changed 27 times since it was ratified in 1788, and the changes made to the Constitution range from sweeping expansions of civil rights to narrow repairs in how the federal government operates.1U.S. Senate. Constitution of the United States Every one of those 27 changes moved through the same demanding process the framers wrote into Article V. The most recent took effect in 1992.
How a Change Gets Made
Article V lays out two stages: proposal and ratification. A proposal usually comes from Congress, requiring a two-thirds vote of the members present in both the House and Senate.2Constitution Annotated. ArtV.1 Overview of Article V, Amending the Constitution The alternative route lets two-thirds of state legislatures call a national convention to propose amendments. No convention has ever been called; all 27 amendments have come through Congress.3National Archives. Constitutional Amendment Process
After Congress passes a proposal, it goes to the states. Ratification requires approval from three-fourths of the states, currently 38 of 50, either through state legislatures or through state conventions, depending on which method Congress specifies. Once the Office of the Federal Register confirms enough ratifications, the Archivist of the United States certifies the amendment as part of the Constitution.3National Archives. Constitutional Amendment Process
Congress usually sets a ratification deadline but is not required to. The Supreme Court held in Dillon v. Gloss (1921) that Congress has authority to fix a time limit.4Constitution Annotated. Congressional Deadlines for Ratification of an Amendment When no deadline is set, a proposal stays technically pending indefinitely. That is how the Twenty-Seventh Amendment, first proposed in 1789, could still be ratified 202 years later.
The Bill of Rights
The first Congress proposed twelve amendments in September 1789. Ten were ratified by the states on December 15, 1791, and became the Bill of Rights.5National Archives. The Bill of Rights – A Transcription One of the two that failed at the time concerned the size of congressional districts and was never ratified. The other, on congressional pay, eventually became the Twenty-Seventh Amendment.
The First Amendment protects speech, the press, religious exercise, peaceful assembly, and the right to petition the government from government interference.6Congress.gov. U.S. Constitution – First Amendment The Second protects the right to keep and bear arms. The Third bars quartering soldiers in private homes. The Fourth guards against unreasonable searches and seizures and requires warrants supported by probable cause.7Legal Information Institute. Fourth Amendment
The Fifth and Sixth Amendments shape criminal procedure. The Fifth protects against being forced to testify against yourself and guarantees that no one can be deprived of life, liberty, or property without due process. The Sixth guarantees a speedy public trial, an impartial jury, and the assistance of a lawyer.8Congress.gov. U.S. Constitution – Sixth Amendment The Seventh preserves jury trials in civil cases, and the Eighth bars excessive bail and cruel and unusual punishments. The Ninth clarifies that listing certain rights in the Constitution does not deny others retained by the people. The Tenth reserves any power not given to the federal government to the states or the people, a single sentence that has anchored federal-versus-state disputes ever since.
The Reconstruction Amendments
The Civil War produced the most transformative changes in the document’s history. The Thirteenth Amendment, ratified in 1865, abolished slavery and involuntary servitude nationwide, with a narrow exception permitting forced labor as criminal punishment.9Congress.gov. U.S. Constitution – Thirteenth Amendment
The Fourteenth Amendment, ratified in 1868, established birthright citizenship for all persons born or naturalized in the United States and barred states from denying anyone equal protection of the laws or depriving any person of life, liberty, or property without due process.10Congress.gov. U.S. Constitution – Fourteenth Amendment Those two clauses have generated more Supreme Court litigation than almost any other constitutional language, and they are the basis for landmark rulings on racial segregation, marriage equality, and government discrimination.
The Fifteenth Amendment, ratified in 1870, barred the federal government and the states from denying the vote based on race, color, or previous condition of servitude.11Congress.gov. U.S. Constitution – Fifteenth Amendment On paper, it enfranchised Black men. In practice, states invented workarounds like literacy tests, poll taxes, and grandfather clauses, and it took nearly a century of additional legislation to enforce the guarantee. The Voting Rights Act of 1965 was enacted specifically to enforce the Fifteenth Amendment by outlawing literacy tests, sending federal examiners to register voters, and requiring certain jurisdictions to get federal approval before changing their voting rules.12National Archives. Voting Rights Act
Amendments That Widened the Vote
Four additional amendments enlarged the electorate, each targeting a specific barrier.
The Nineteenth Amendment, ratified in 1920, prohibited denying the vote on account of sex, roughly doubling the eligible voting population.13National Archives. 19th Amendment to the U.S. Constitution – Women’s Right to Vote
The Twenty-Third Amendment, ratified in 1961, gave residents of the District of Columbia the right to vote for President and Vice President by granting the District a number of electoral votes equal to what it would receive if it were a state, capped at the number held by the least populous state.
The Twenty-Fourth Amendment, ratified in 1964, banned poll taxes in federal elections. Several states had used those fees to keep low-income citizens, disproportionately Black voters, from casting ballots.
The Twenty-Sixth Amendment, ratified in 1971 during the Vietnam War, lowered the voting age from twenty-one to eighteen.14Congress.gov. U.S. Constitution – Twenty-Sixth Amendment
Structural Fixes to Federal Offices
Other amendments repaired mechanical problems in how government operates. Less dramatic than the rights amendments, some resolved genuine crises.
The Twelfth Amendment, ratified in 1804, came out of the 1800 presidential election, when Thomas Jefferson and Aaron Burr each received 73 electoral votes and the tie went to the House over 36 ballots. The amendment required electors to cast separate ballots for President and Vice President.15Congress.gov. U.S. Constitution – Twelfth Amendment
The Seventeenth Amendment, ratified in 1913, moved the selection of Senators from state legislatures to direct popular election.16Congress.gov. U.S. Constitution – Seventeenth Amendment
The Twentieth Amendment, ratified in 1933, shortened the gap between Election Day and the start of new terms. Presidential and vice-presidential terms now begin at noon on January 20; congressional terms begin on January 3.17Legal Information Institute. 20th Amendment Before the change, outgoing officials served until March, producing a long lame-duck period.
The Twenty-Second Amendment, ratified in 1951, capped presidential service. No one can be elected President more than twice, and a person who has already served more than two years of someone else’s term can be elected only once on their own.18Congress.gov. U.S. Constitution – Twenty-Second Amendment Franklin Roosevelt’s four consecutive victories prompted the change; before that, the two-term limit existed only as an unwritten tradition begun by George Washington.
The Twenty-Fifth Amendment, ratified in 1967, addressed two gaps the original Constitution left dangerously vague. Section 2 created a process for filling a vacant vice presidency: the President nominates a replacement, who takes office after a majority vote of both houses of Congress.19Congress.gov. Twenty-Fifth Amendment Section 2 That procedure was used twice within two years when Spiro Agnew resigned and Gerald Ford was confirmed, then Ford became President and Nelson Rockefeller was confirmed to replace him. Section 4 handles a darker scenario: the Vice President and a majority of the Cabinet can declare the President unable to discharge the office’s duties, and the Vice President becomes Acting President. If the President disputes the declaration, Congress decides, and a two-thirds vote in both chambers is required to keep the President sidelined.20Congress.gov. Overview of Twenty-Fifth Amendment, Presidential Vacancy and Disability
The Twenty-Seventh Amendment, ratified in 1992, prevents any law changing congressional compensation from taking effect until after the next election of Representatives.21Congress.gov. U.S. Constitution – Twenty-Seventh Amendment Its ratification period, 202 years, 7 months, and 12 days, is the longest of any amendment.
Policy and Revenue Amendments
A handful of amendments addressed specific policy questions.
The Eleventh Amendment, ratified in 1795, stripped federal courts of the power to hear lawsuits filed against a state by citizens of another state or by foreign nationals.22Constitution Annotated. Eleventh Amendment It was a direct response to the Supreme Court’s decision in Chisholm v. Georgia (1793), which had allowed exactly that kind of suit.
The Sixteenth Amendment, ratified in 1913, authorized Congress to collect a federal income tax without dividing the revenue proportionally among the states based on population.23Congress.gov. U.S. Constitution – Sixteenth Amendment The original Constitution required direct taxes to be apportioned by state population, which made a national income tax effectively impossible.
The Eighteenth Amendment, ratified in 1919, banned the manufacture, sale, and transport of alcoholic beverages nationwide.24Legal Information Institute. 18th Amendment Prohibition lasted fourteen years. The Twenty-First Amendment repealed it in 1933, returning alcohol regulation to the states.25Constitution Annotated. Overview of Twenty-First Amendment, Repeal of Prohibition The Twenty-First is the only amendment ratified through state conventions rather than state legislatures. Supporters of repeal chose that route because temperance groups still held sway over many state legislators.
Proposals That Did Not Become Part of the Constitution
Not every amendment that clears Congress makes it in. Thousands of amendments have been proposed; only 33 received the required two-thirds vote in both chambers, and 27 were ratified.
The most prominent failure is the Equal Rights Amendment, which Congress proposed in 1972 with a seven-year ratification deadline later extended to 1982. The ERA would have guaranteed equal legal rights regardless of sex. Virginia became the 38th state to ratify in 2020, technically reaching the three-fourths threshold, but the deadline had long since expired. The Department of Justice’s Office of Legal Counsel has taken the position that the deadline is binding and that the ERA did not become part of the Constitution. Efforts to recognize the amendment or restart the process remain active in Congress.26Congress.gov. Establishing the Ratification of the Equal Rights Amendment
The District of Columbia Voting Rights Amendment, proposed in 1978, would have given D.C. full congressional representation as if it were a state. It expired in 1985 after only 16 states ratified. A few older proposals technically remain open because Congress never set a deadline. The Titles of Nobility Amendment, passed by Congress in 1810, would have stripped citizenship from anyone accepting a foreign title of nobility; it has been dormant since falling short at the time, but no deadline was ever attached.
Change Without an Amendment
The 27 formal amendments are only part of how the Constitution has changed. Its meaning has also shifted through Supreme Court decisions interpreting the existing text. The foundation for that power comes from Marbury v. Madison (1803), in which the Court declared that “it is emphatically the province and duty of the judicial department to say what the law is” and that any ordinary legislation conflicting with the Constitution must yield.27Constitution Annotated. ArtIII.S1.3 Marbury v. Madison and Judicial Review Under that principle, known as judicial review, the same constitutional language can produce different legal outcomes across eras. The Fourteenth Amendment’s equal protection guarantee, for example, was once read to permit racial segregation and is now read to forbid it. No word of the text changed; the Court’s interpretation did.