The presidential election in the United States this year is, yet again, a contest between two men. But in Latin America, as Mexico’s milestone election showed over the weekend, electing a woman as president has become remarkably routine.

Claudia Sheinbaum, who won Mexico’s election in a landslide against another female candidate, Xóchitl Gálvez, joins at least a dozen other women who have served as presidents of Latin American countries since the 1970s.

This growing list includes past leaders of two of Latin America’s largest countries, Dilma Rousseff of Brazil and Cristina Fernández de Kirchner of Argentina, and those in smaller nations like Violeta Chamorro of Nicaragua and Xiomara Castro, the current president of Honduras.

The ascension of women to such heights spotlights how some democracies in Latin America that emerged from the ashes of authoritarian rule have proven exceptionally open to tearing down barriers to political representation.

Jennifer Piscopo, a professor of gender and politics at Royal Holloway, a college at the University of London, said that women who had become president in Latin America generally followed a pattern of being nominated by incumbent parties already enjoying high levels of voter support.

Citing the examples of Ms. Rousseff in Brazil, Michele Bachelet in Chile and Laura Chinchilla in Costa Rica, Ms. Piscopo said such parties “enjoy the best of both worlds,” first by reaping electoral benefits from their strong reputation going into an election.

And second, “they can also use women to signal novelty or change to the electorate,” Ms. Piscopo said.

In Mexico, the governing party, Morena, has steadily expanded its power around the country in recent years while enshrining gender parity in politics as a pillar of its ambitions to bring change to the world’s largest Spanish-speaking country.

While women in Mexico didn’t gain the right to vote until 1953, the country now stands apart from others in the region with an assortment of policies and legislation aimed specifically at opening the way for women in politics.

The efforts picked up steam after a landmark election in 2000 ended decades of authoritarian rule. Quotas allowed more women to run for office, then a 2019 constitutional amendment, supported by a far-reaching coalition of female activists, scholars and politicians, set parity goals in legislative, judicial and executive branches.

Just a few years later, Mexico not only has a female president-elect but also women at the helm of both houses of Congress, where women held half the legislative seats going into this election. Women also serve as chief justice of the Supreme Court and governor of the Central Bank.

Efforts to achieve equality reverberated through local and state elections. In a reflection of the presidential race, contests for governor in Guanajuato and Morelos states also saw two women vying to win.

The entry of more women into politics is reflected in landmark policy shifts, such as Mexico’s decriminalization of abortion nationwide in 2023. Mexico joined countries such as Argentina, Colombia, Guyana and Uruguay that have moved to expand abortion rights.

Still, Latin America’s recent history also holds cautionary tales about how easily women can fall from rarefied positions of power.

In Brazil, for instance, a similar situation to this year’s election in Mexico, where Ms. Sheinbaum was the protégée of a broadly popular male president, played out in 2010 when Ms. Rousseff, the former chief of staff to Luiz Inácio Lula da Silva, won the presidential election.

Ms. Rousseff went on to win re-election in 2014. But in the wake of huge corruption scandals involving her leftist party and economic weakening, she then faced an open revolt among lawmakers. The backlash resulted in her impeachment on charges of manipulating the budget to conceal economic problems and her removal from office in 2016.

The ouster paved the way for the rise to the presidency of Jair Bolsonaro, a far-right figure who made verbal attacks on women a staple of his tenure.

After her impeachment, Ms. Rousseff ran for a Senate seat in 2018 and lost. After Mr. Lula returned to the presidency last year, she also re-emerged, as chair of a development bank founded by Brazil, China, India, Russia and South Africa.

“It is not just about holding the position,” said Mónica Tapia, founder of Aúna, a Mexican incubator of political leadership for women. “It’s also about having the power and autonomy to control the agenda and the legacy women want to leave.”

Emiliano Rodríguez Mega contributed reporting.