The 19th Amendment to the United States Constitution, guaranteeing American women the right to vote, celebrates a big birthday on Tuesday, as it was passed by both chambers of Congress 100 years ago on June 4, 1919. According to the National Archives, the House of Representatives first passed the amendment on May 21, 1919, and two weeks later, on June 4, the Senate followed with a vote of 56 to 25. The next year, following approval by three-fourths of state legislatures, the amendment was ratified into the Constitution.