Which constitutional amendment prohibited denying U.S. voting rights based on sex?

The Nineteenth Amendment prohibited the United States and its states from denying citizens the right to vote on the basis of sex.

The amendment was the national constitutional achievement of a suffrage movement that had developed over many decades. Activists organized conventions, petition drives, state campaigns, and national lobbying efforts. Some states and territories had already extended voting rights to women, but national protection required a constitutional amendment.

Congress passed the proposal in 1919. Tennessee became the decisive thirty-sixth state to ratify it on August 18, 1920, supplying the three-fourths approval then required. Secretary of State Bainbridge Colby certified the amendment on August 26, 1920.

The amendment did not immediately eliminate every barrier to voting. Many women of color, especially Black women in the South, continued to face discriminatory laws and intimidation. Later federal legislation and court decisions were necessary to challenge those practices. The amendment’s wording addresses sex-based denial of voting rights, not every form of voter suppression.