When Kamala Harris took the oath of office yesterday as vice-president, no serious commenter could question her legal eligibility on the basis of her sex. But for more than a century, Americans bitterly disputed this precise point. Historically, meaningful challenges to women's officeholding rights typically arose only upon their victories. Thus, Harris's win, as well as her identity as a lawyer, a woman of colour and a representative of a Western state provide a prime opportunity to highlight key aspects of women's long fight for equal political rights.

A woman was first elected to public office in the United States in 1853, a time when no women could vote. The men of Lincoln County, Maine, selected Olive Rose as their register of deeds. Newspapers covered this milestone with a mix of jubilation and unease. "Maine has taken the lead" in advancing women's rights, one writer proclaimed, before expressing concern that Rose's election initiated a slippery slope towards the first female president. Once men "let the ladies get the upper hand", he speculated, "we may see the supreme power of the State usurped by a strong-minded" suffragist. He cautioned facetiously against "a female coup d'etat". Despite some questions about Rose's eligibility, no one formally challenged her election — in part because observers believed that male voters should have the right to choose their preferred candidate.

Whether women could legally hold public offices, including the office of president, remained a point of contestation for generations. Most discussion occurred at the state level. Some state constitutions unambiguously barred women from serving as officers, through language limiting officeholding to "male citizens" or stating that only those eligible to vote could hold office, which indirectly excluded women. For example, Ohio's 1851 Constitution read: "No person shall be elected or appointed to any office in this State, unless he possess the qualifications of an elector", and electors were limited to men. Other state constitutions lacked such rules, leaving the issue open to argument. For instance, Pennsylvania's Constitution, as amended in 1857, contained residency and age requirements for officeholders, but it did not expressly limit officeholding to men or to voters.

In states where the law did not clearly permit or forbid women's officeholding, women who were elected or appointed to positions lodged lawsuits to demand access to their posts. Some of the earliest female lawyers secured wins in the Midwest and West, but in New England the judiciary concluded that women could not hold office because state constitution drafters had never intended that result.

Women's officeholding wasn't just a legal issue. It was also a political one. Concern about officeholding permeated women's suffrage debates. Anti-suffragists claimed that the inevitable path from voting to officeholding would "unsex" women and put them in unhealthy competition with men. The allure of officeholding was therefore a reason to keep women away from the ballot box. Meanwhile, suffragists strategically disclaimed their desire to hold office, even as some did seek state constitutional amendments to obtain access to certain posts.

Women's eligibility for president and vice-president was less contentious than for state positions, probably because the latter seemed more likely for women to win. Notably, the US Constitution's text did not provide a strong basis to exclude female candidates. Article II Section 1 specifies only that the president must be a US citizen, at least 35 years old and a US resident for 14 years. (The same rules implicitly apply to the vice-president.) And yet, congressmen and concerned citizens nonetheless claimed women were disqualified, usually by pointing to the founders' imagined intent or to male pronouns. However, since male pronouns were commonly used as universal and the founders did not directly address this question, one fair reading was that the Constitution did not include a sex-based restriction.

When women first campaigned for president and vice-president — in symbolic third-party efforts — it was obvious they would not win and so there was little discussion of eligibility. In 1872, Victoria Woodhull was nominated for president by the Equal Rights Party. As one of the first women stockbrokers, the co-founder of a controversial newspaper and a supporter of several causes viewed as radical at the time — such as free love — Woodhull received significant publicity some viewed as harmful to the women's suffrage cause.

In 1884, Belva Ann Lockwood ran for the top spot and tapped Marietta Stow as her running mate, again on the Equal Rights Party ticket. Both were well-connected suffragists, and Lockwood insisted there were no constitutional impediments to their service. A few years earlier, Lockwood had become the first woman to join the US Supreme Court bar, and Stow had run for governor of California. The duo's platform prioritised equal suffrage and women's access to federal offices.

Some of the most striking exchanges about women's political rights occurred shortly after these long-shot campaigns, in congressional debates over admitting Wyoming territory as a state in 1890. The proposed state constitution authorised women "to vote and hold office", leading congressmen to worry that Wyoming would elect women to sit beside them and aim for the presidency. A Southern senator protested this provision by claiming that male pronouns in the US Constitution obstructed "the way of our aspiring ladies to the presidency of the United States". In the House, one representative charged that opponents of women's political rights actually feared that they might "some day see sitting in the presidential chair of the nation a woman with a Black skin".

That a member of Congress used the spectre of a Black female president for dramatic effect is particularly revealing of the dynamics of the time, as no Black woman had run for the presidency and, indeed, Black women faced significant political and social impediments to officeholding because of their intersectional identities. Although no officeholding law distinguished between women on the basis of race, the Jim Crow laws and violence that deprived Black men of full political equality constrained Black women as well. Moreover, Black Americans disproportionately lived in the South, a region not welcoming to any women officeholders. Nevertheless, a handful of Black women did succeed in securing offices by the turn of the century. For example, several were appointed by governors as notaries public, one of the offices that most frequently sparked women's eligibility litigation. Still, a Black female president would not have seemed realistic to most Americans at the time.

By the early 20th century, some prominent men endorsed women's presidential ambitions. In 1905, US Supreme Court Justice David Brewer made headlines for his outspoken support of an eventual female president. Noting that women were already voting in four states, he told a journalist: "I can see no good reason there should not be a female president of the country. I can see a great many good reasons why there should be one." This stance was in line with Brewer's earlier jurisprudence. When he sat on the Supreme Court of Kansas in 1876, he authored one of the first opinions favouring women's officeholding eligibility, dismissing the argument that women's rights should be constrained by constitution drafters' expectations.

By the mid-1910s, Western states — including Harris's home state of California — had enfranchised women, which sparked greater consideration of women's path to high offices. As early as 1900, leading suffragist Susan B. Anthony had predicted that the first congresswoman would come from the West, "that part of the country being less conservative than the East". Her guess proved correct in 1916, when Montana voters elected Jeannette Rankin to the House. Commenters questioned Rankin's eligibility, but it was widely recognised that the House wouldn't dare exclude her for fear of Western women voters' wrath.

Although ratification of the 19th Amendment in 1920 barred discrimination in voting "on account of sex", it neither ensured all women's equal political rights nor guaranteed their access to public offices. Both women and men of colour were widely and purposely disenfranchised. As historians have powerfully detailed, Black women had to continue fighting for the ballot. Moreover, naysayers about women's officeholding continued to point to male pronouns to maintain that the Constitution's framers hadn't envisioned a female president. As late as 1953, Secretary of State John Foster Dulles found it "at least debatable whether under our Constitution a woman can be President".

Since then, of course, dozens of women have made serious runs for president or vice-president, with four — Geraldine Ferraro, Sarah Palin, Hillary Clinton and Harris — making it on to a major party's presidential ticket. A Black woman first appeared on a presidential ticket in 1952, when Charlotta Bass served as the Progressive Party's nominee for vice-president. These women's eligibility to run was not legally challenged, although the relevance of the Constitution's male pronouns continues to feature in debates over originality.

Harris's victory strikingly punctuates women's long battle for equal political rights, reminding us of the importance of sex, race, region and law in the nation's history. Generations of path-breaking women made Harris's election possible and the inauguration of a women president in the near future probable — a prominent, powerful triumph for equality.

• Elizabeth D. Katz is an associate professor of law at Washington University in St Louis and an expert in women's legal history