What is notable about Jeannette Rankin's election to Congress?

Jeannette Rankin's election to Congress is particularly notable because she is the only member of Congress to oppose both World Wars. Her pacifist stance led her to vote against the U.S. entry into World War I in 1917 and again against entering World War II in 1941. Rankin's commitment to her beliefs reflected her dedication to peace and her significant role as a trailblazer for women in politics, emerging as one of the first women elected to the federal legislature. This aspect of her career highlights not only her unique position in American history but also underscores the broader themes of advocacy for peace during tumultuous periods.

As for the other options, while women gained the right to vote prior to her second term, her first election occurred before this milestone, making the first choice inaccurate in that context. Rankin was not a Cabinet member but rather served in Congress, which makes the second option incorrect. Additionally, she served in the early 20th century and well after the Civil War, rendering the last option invalid.