Which U.S. constitutional amendment, ratified in 1920, prohibited denying citizens the vote based on sex?

The Nineteenth Amendment prohibited the United States and its states from denying citizens the vote based on sex.

Congress approved the amendment in 1919, and Tennessee became the 36th state to ratify it on August 18, 1920. That ratification supplied the three-fourths majority then required for constitutional amendments. The amendment was formally certified on August 26, 1920.

Its adoption followed decades of organizing by women’s suffrage activists. The 1848 Seneca Falls Convention helped launch the modern American women’s rights movement, while campaigners including Susan B. Anthony, Elizabeth Cady Stanton, Ida B. Wells, and Alice Paul used petitions, speeches, protests, and legal arguments to press for voting rights.

The amendment was a major constitutional milestone, but it did not immediately remove every barrier to voting. Many African American women, Native American women, Asian American women, and Latina women continued to face discriminatory laws and practices. The Nineteenth Amendment guaranteed the right in constitutional text; enforcement required further struggles.