On June 4, 1919, Congress passed the 19th Amendment to the United States Constitution. Passage in the House and Senate activated the ratification process, in which each state legislature would vote for or against.
The amendment was adopted in August 1920. Finally, after nearly a century of direct and indirect action by organized women, along with some men, the right to vote was protected regardless of sex.
Still, not all women had full voting rights and protection in 1920. Laws discriminating against race and class did — and some still do — exist to stop women from voting in spite of the new amendment.
See the Joint Resolution from National Archives.