She was elected to Congress in 1916, and she voted against the United States declaration of war in World War I.
Districting (not re-districting) from two at-large respresentatives for the whole state to representatives representing districts led her to run for Senate and lose in 1918.
But she was re-elected in 1940, just in time to vote against the United States declaration of war in World War II. Which led to her being voted out in 1942.
When Whatever Became Of…? came out, she was an octogenarian leading protest marches against the war in Vietnam.
The book gives this tidbit:
When World War II broke out Miss Rankin again ran for Congress from the state of Montana and was elected on the Republican ticket. “I’ve always been a Republican,” she says, “for the same reason that most people are either Democrats or Republicans–because their fathers were one or the other. Frankly, I cannot see a particle of difference between the two.”
The book says she won her first election on a women’s suffrage ticket and implies the change in party was for political expediency, but the Wikipedia makes it sound a little more complicated than that.
However, the quote could be something you hear today about the uniparty in Washington, and the allegation of running as a member of the opposite party to get elected and then caucusing with your true party in office rings true as we’ve seen here locally that sort of behavior from Democrats who cannot win election as Democrats trying to get elected as Republicans (such as Jim Evans, whose declaration of his Republican bonafides kind of align with Rankin’s).
So that’s the answer to the trivia question “What U.S. Congresswoman voted against World War I and World War II?” Not that anyone will ever ask.