The campaign for female suffrage was almost universal in the western world. Whilst some US states permitted female voters very early, in certain states and at the national level the campaign was very fierce. The nineteenth amendment to the constitution was ratified on 18 August 1920:
"The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of sex. Congress shall have power to enforce this article by appropriate legislation."