Thanks to Susan B. Anthony and Elizabeth Cady Stanton who drafted what is now the 19th Amendment to the U.S. Constitution. This amendment prohibits any U.S. citizen from being denied the right to vote on the basis of sex.
On June 4, 1919, the proposal to amend the Constitution was passed in House of Representatives 54-25. The amendment was ratified on August 18, 1920. The Supreme Court upheld the validity of the 19th Amendment in Leser v. Garnett. A second shout-out goes to Justice Brandeis for authoring that Supreme Court opinion.