That’s the conventional version of the history, and it’s wrong.
The first clue that there’s something inaccurate about this story is that Jeannette Rankin, the first woman to be elected to the United States Congress, was elected in 1916.
It would indeed be odd if women were being elected to Congress at a time when women were not allowed to vote.
In fact, in Jeannette Rankin’s home state of Montana, women had been voting since 1914. Women in Montana had full voting rights, in every way equal to men, more than six years prior to the passage of the Nineteenth Amendment.
But Montana was late to the party. Women had obtained full suffrage in Wyoming in 1869, and in Colorado in 1893. Utah and Idaho recognized full suffrage for women in 1896.
In fact, prior to the passage of the Nineteenth Amendment, approximately 85% of the women in the United States were enfranchised. There were only seven of the 48 states in which women did not vote (Pennsylvania, Maryland, Virginia, West Virginia, North Carolina, South Carolina, and Alabama).
Women were already voting from New Jersey and Delaware to Oregon and California, from Minnesota and North Dakota to Texas and New Mexico - long before the Nineteenth Amendment.
While responsible historians do not speculate about counterfactual situations, it is clear that in those seven states which had not yet enfranchised women, legislative movements were underway to do just that. Even without the Nineteenth Amendment, the franchise would probably have expanded to the last 15% of women in the United States.
To say that 85% of the women had the vote prior to the Nineteenth Amendment may even be too low, because the seven states in which they didn’t vote had an average population lower than the 41 states in which they did vote. It was possibly closer to 90% than to 85%.
In some regions, more women were voting than men! Especially during wartime, when many men were away from home.
Women’s ability to vote, then, is not due to actions at the federal level in the early 1900s, but is rather due to actions at the state level in the late 1800s.
The United States led the way. Other nations around the globe didn’t give women the right to vote until much later: Women in the U.S. had been voting for 24 years before women in New Zealand got the right to vote in 1893. Other nations - Austria, Australia, Finland, Norway, Denmark, Germany, Poland, Netherlands, Sweden, etc. - waited until the early 1900s.
The political party which had been formed to abolish slavery in the United States, having accomplished that objective by 1863, made women’s suffrage its next major goal: the states which led the way - Wyoming, Montana, Idaho, Colorado, and Utah - were largely populated by voters of that party.
While generations of schoolchildren have memorized the year 1920, it would be more accurate to cite 1869 as the year when women began to vote in the United States.