The National American Woman Suffrage Association (NAWSA) was an organization formed on February 18, 1890, to advocate in favor of women's suffrage in the United States. It was created by the merger of two existing organizations, the National Woman Suffrage Association (NWSA) and the American Woman Suffrage Association (AWSA). Its membership, which was about seven thousand at the time it was formed, eventually increased to two million, making it the largest voluntary organization in the nation. It played a pivotal role in the passing of the Nineteenth Amendment to the United States Constitution, which in 1920 guaranteed women's right to vote.

Women's suffrage, or the right to vote, was established in the United States over the course of more than half a century, first in various states and localities, sometimes on a limited basis, and then nationally in 1920 with the ratification of the 19th Amendment to the United States Constitution.