The 19th Amendment to the United States Constitution was ratified on August 18, 1920, and granted women the right to vote. Three factors that led to the passage of the 19th Amendment include:
1. Suffrage movements: The suffrage movements, which had been gaining momentum since the mid-19th century, played a significant role in advocating for women's right to vote. Organizations such as the National American Woman Suffrage Association (NAWSA) and the National Woman's Party (NWP) organized marches, protests, and lobbying efforts to push for suffrage legislation.
2. World War I: During World War I, women took on significant roles in the workforce and in supporting the war effort. This increased visibility and contributions of women highlighted the need for their voices to be heard in the political sphere as well. The wartime efforts of women helped build support for suffrage among the general public.
3. Changing social attitudes: By the early 20th century, social attitudes towards women's rights were gradually shifting. Women were becoming more educated, independent, and active participants in society. The growing recognition of women's contributions and capabilities helped to erode traditional beliefs that women were not fit to participate in the political process.
Overall, a combination of grassroots activism, changing societal norms, and the efforts of women during World War I ultimately led to the passage of the 19th Amendment and the expansion of voting rights to include women in the United States.