On June 4, 1919, the US Congress approved the 19th Amendment, which granted suffrage to women. The Amendment was not ratified by the states until August 18, 1920, but the approval was a huge victory for women’s rights. Susan B. Anthony and Elizabeth Cady Stanton first drafted and introduced the amendment in 1878, but it took over forty years for women to get the right to vote.
Before that, the rules of suffrage were undefined by the Constitution, though most states did not extend the vote to women (New Jersey being the exception, though they revoked women’s suffrage in 1807). Though the amendment was introduced in 1878, Congress repeatedly ignored it, and the fight for women’s suffrage moved to the states. Beginning in 1910 a number of western states passed legislation for full or partial suffrage for women.
The Woman Suffrage Party was organized by Carrie Chapman Catt in 1909 out of many small suffrage societies. It put the state legislature under intense pressure in 1913, forcing a referendum on votes for women in New York State. In 1915, a second vote was forced by more campaigning, helping women gain the vote in New York state. With the momentum started in New York and the added votes from women in the state, New York carried the country and the 19th Amendment was finally approved by Congress.
Then it was up to the states to ratify it; 3/4 of the states needed to ratify it for it to become part of the Constitution (meaning 36 of the 48 existing states). There were a few holdouts–Virginia, Alabama, Florida and South Carolina did not ratify the amendment until the 1950s and 1960s, and Mississippi was the last to ratify it, waiting until 1984!