Which party voted for first women in Congress?

1. The simple answer: the first woman in Congress was a Republican

Every major institutional source in the provided reporting identifies Jeannette Rankin — the first woman elected to the U.S. Congress — as a Republican, elected from Montana’s at-large seat in the 1916 election and taking her seat in 1917 ^{[2] [1] [3]}. The U.S. Senate’s historical summary and the House history both mark Rankin as the trailblazing Montana Republican whose election predated the national ratification of the Nineteenth Amendment ^{[2] [4]}.

2. But the label needs context: “Progressive Republican” and suffrage activism

Rankin’s campaign and public identity are often described in the sources as Progressive Republican and deeply tied to the suffrage movement; she had worked as a field secretary for NAWSA and helped secure Montana women the vote before running for Congress, which shaped her base and platform ^{[1] [5]}. Contemporary outlets and later historians therefore distinguish her Republican party label from the broader Progressive-era reformist politics that animated many early women officeholders ^{[1] [6]}.

3. Why the party label matters — and why it can be misleading across eras

Saying the “Republican Party” elected the first woman is factually accurate in party-label terms, but it risks flattening political change: early 20th-century Republicans included a sizable Progressive wing that is not identical to today’s GOP, and Rankin’s single-minded suffragist and pacifist commitments put her at odds with many members of both parties during World War I debates ^{[1] [4]}. Institutional histories therefore pair the party designation with explanations of the Progressive era and suffrage politics to avoid conflating 1916 party coalitions with 21st-century alignments ^{[2] [4]}.

4. What Rankin’s party affiliation did — and did not — mean for women’s political representation

Rankin’s Republican label did not signal a partisan monopoly on women’s political firsts; later milestones in women’s congressional history cut across parties — for example, Margaret Chase Smith, another Republican, later became the first woman to serve in both houses, while Democratic women would go on to hold many other “firsts” in subsequent decades ^{[7] [8]}. Sources documenting milestones and the slow growth of women in Congress emphasize that party affiliation was only one part of a longer, bipartisan story of expanding women’s representation ^{[8] [4]}.

5. The counterpoint and what sources caution against assuming

Histories in the record warn against assuming modern partisan meaning from a 1916 label: Rankin’s identification as a Republican appears everywhere in the provided reporting, yet scholars and archives emphasize her Progressive and suffragist identity and note that her antiwar votes made her controversial across party lines rather than a standard-bearer for a unified party position on women in office ^{[1] [4] [5]}. The supplied sources do not attribute Rankin’s election solely to Republican party machinery, instead pointing to mass suffrage activism in Montana and broader Progressive politics ^{[5] [6]}.

6. Bottom line for readers following the party question

Stick to the institutional facts: the first woman elected to serve in the U.S. Congress, Jeannette Rankin, was elected as a Republican (often described contemporaneously as a Progressive Republican) in 1916 and sworn into the House in 1917 ^{[2] [1] [3]}. The fuller historical picture in the sources shows that her election was rooted in suffrage mobilization and Progressive-era politics, and later women’s firsts cut across party lines, so the Republican label is accurate but not dispositive of the broader story ^{[5] [8] [7]}.