On Feb. 15, 1820, 201 years ago today, the famous American suffragist Susan B. Anthony was born in Adams, Mass. This year, her birthday follows the centennial of the ratification of the 19th Amendment, which banned denying the right to vote “on account of sex.” In November 1920, just more than two months after the 19th Amendment’s ratification, millions of women cast their ballots for the first time.

The 19th Amendment did not fully enfranchise women overnight. The amendment did little to enfranchise Black women in the South, who continued to be barred from voting in practice by Jim Crow techniques such as poll taxes, literacy tests and violence. But however partial, the amendment roughly doubled the U.S. population eligible to vote, a major extension of civil rights.

New research finds that women’s suffrage changed the country significantly, in ways often overlooked. Government expanded public education and enacted robust public health measures to reduce child mortality. And as women’s suffrage spread from one country to another, it transformed international relations, too, in ways that social scientists are only beginning to understand.

Women’s suffrage helped build the U.S. welfare state

In the 1920s, women at first turned out to vote at much lower rates than men, but the amendment nonetheless was the largest expansion of the electorate in U.S. history. Soon, politicians started responding to what they believed these new voters wanted.

Within a year of the extension of suffrage, for example, Congress passed the 1921 Sheppard-Towner Act, a landmark public health bill for which women’s organizations had lobbied. As politicians responded to what they believed the new electorate wanted, legislators’ voting patterns changed rapidly, and local public health spending rose by about 35 percent. This helped scale up mass door-to-door campaigns to promote simple hygienic practices such as hand-washing and boiling water, which rapidly reduced rates of deadly infections such as diphtheria and diarrheal diseases. Within a year of suffrage, child mortality declined by an estimated 8 to 15 percent, the equivalent of about 20,000 deaths a year.

Suffrage also led to an increase in education spending, as well as other types of state government expenditures, which kept increasing as more women voted. In fact, some research attributes up to a third of the rise in public school expenditures between 1920 and 1940 to the 19th Amendment. Children stayed in school longer and disadvantaged children did better in school, especially Black and Southern White children, as education spending increased disproportionately for these groups from very low levels. Women’s suffrage had a similar effect in Western Europe, where it also substantially boosted social spending. One study concludes that female voting power helped push public funding “away from ‘guns’ and into ‘butter.’”

Women’s suffrage pacified international relations

The women’s vote also affected foreign policy. Polls show that American women have consistently been less likely to support U.S. military interventions and more likely to support peaceful policies than men. The political scientist Joshua Goldstein has shown that across times and nations, on average, women are less inclined toward violence than men — even if individual women and men, or subgroups of them, might differ from that average.

The Suffragist Peace,” a new study by Joslyn N. Barnhart, Robert F. Trager, Elizabeth N. Saunders and Allan Dafoe, includes a meta-analysis of recent survey experiments by international relations researchers, spanning 20,000 survey respondents in six countries spread over four continents. They found that in all 17 studies they analyzed, women were significantly less likely to support using military force. Of course, women’s political preferences are not homogeneous, and in several of the studies, more than 50 percent of them supported the use of force. Yet despite some variation in the size of the gender gap — it was largest in Japan and smallest in Israel — it was found in every region and cultural context the researchers investigated.

It may come as little surprise, then, that as women gained the right to vote, international relations became more peaceful. In the same study, the researchers found that between 1816 and 2010, democracies where women could not vote were 192 percent more likely to start conflicts than democracies where women could vote. Two democracies with women’s suffrage were about one-third as likely to militarize a dispute as two democracies without the women’s vote, and about one-fourth as likely as two autocratic countries. Women’s suffrage tended to promote peace even before World War II, suggesting that the pattern is unlikely to result from the postwar period’s economic interdependence, international institutions and nuclear weapons, which are often considered reasons for the 20th century’s long, if uneven and uneasy, peace.

None of this is to say, however, that female leaders are inherently peaceful. In fact, female presidents and prime ministers can find themselves pushed to combat gender stereotypes by adopting hawkish policies. And research by Joshua A. Schwartz and Christopher W. Blair shows that female leaders have reasons to “act tough,” which may make it harder for them to back down from threats in international crises. But in general, the rise of women’s suffrage in democracies around the world may have helped to usher in a more peaceful era.

Today, the United States has 24 female senators and 118 congresswomen — more women in Congress than ever before, although still barely more than a quarter of the legislature, well below the proportion in most developed democracies. Kamala D. Harris was recently inaugurated the first female vice president of the United States, but unlike Germany, the United Kingdom, India, Indonesia, Israel or Pakistan, the United States has never had a female commander in chief. Over the past century, the expansion of women’s suffrage has created a better educated, healthier and more peaceful world — but in the United States, gender equality in positions of political power still remains some way off.

Bryan Schonfeld is a PhD candidate in politics at Princeton University.

Sam Winter-Levy is a PhD candidate in politics at Princeton University.