Jeannette Rankin was the first woman elected to the U.S. Congress in 1916 by the state of Montana. A Republican and a pacifist, she spoke out fiercely against U.S. military intervention. Rankin was not seated in Congress until April 2, 1917 due to a prolonged discussion about whether a woman should be admitted into Congress. As History.com notes:
Finally, on April 2, 1917, she was introduced in Congress as its first female member. The same day, President Woodrow Wilson addressed a joint session of Congress and urged a declaration of war against Germany. On April 4, the Senate voted for war by a wide majority, and on April 6 the vote went to the House. Citing public opinion in Montana and her own pacifist beliefs, Jeannette Rankin was one of only 50 representatives who voted against the American declaration of war. For the remainder of her first term in Congress, she sponsored legislation to aid women and children, and advocated the passage of a federal suffrage amendment.
Rankin went on to become a figure in the suffrage and pacifist movements. She was elected to Congress for a second term in 1940. Rankin passed in 1973 at the age of 93.