Harriet Tubman won an online poll of who the first woman on U.S. currency should be, and she seems to be the leading choice all-around. PHOTOGRAPH COURTESY LIBRARY OF CONGRESS / AP

“Have you given any thought to the woman who should be on the ten-dollar bill?” Brianna Kellar asked Hillary Clinton recently. “You know, I am very torn about it,” Clinton replied. “I want a woman on a bill. I don't know why they take the ten-dollar bill. Some people are now agitating for the twenty-dollar bill.” Indeed, ever since the Secretary of the Treasury, Jack Lew, announced, last month, that the next version of the ten would feature a woman, that has been the baffled response. Alexander Hamilton, as the musical opening for previews on Broadway this week reminds us, has much to recommend him: he was the immigrant son of a single mother who became a founding father and the architect of our financial system. Why take him off the ten, and leave Andrew Jackson, who brutalized Native American communities, defended slavery, and opposed a national paper currency, on the twenty? A group called Women on 20s had already been organizing a drive to get Jackson off and a woman on. Harriet Tubman won the group’s online poll of who that woman should be, and she seems to be the leading choice all-around. Even Miss Oklahoma named her, when asked in the interview section of the Miss U.S.A. pageant this weekend, after regretting that Oprah was not eligible (under the rules, you have to be dead)—an answer that helped her win the title. Worse, Lew said that Hamilton's defenders shouldn't worry: he'd still be on the ten, sharing it with the yet-to-be-determined woman. (Clinton: “That sounds pretty second-class to me.”) Half of a ten is just a five.

What would it mean to recognize Harriet Tubman with just five dollars? Maybe ask it another way: what would five dollars mean to Harriet Tubman? And what might twenty have meant instead?

In 1845, Araminta Ross Tubman paid five dollars to a lawyer in Maryland, and asked him to look up the will of a man named Atthow Pattison. She was a slave, in her early twenties, but she had somehow got the money together. She apparently hoped that it would be enough to free her mother, Harriet Green, known as Rit, whom Pattison had owned and whom, Tubman suspected, he had intended to free. The lawyer told her that, legally, she was right: Pattison had left Green to his granddaughter, but stipulated that she should be freed when she reached the age of forty-five. Rit Green was much older than that already—the will had been written in 1791—but his granddaughter’s family was still holding her as their property. (The will also said that Rit’s children were supposed to be freed when they turned forty-five, another provision that their owners buried.) As Tubman’s biographer Catherine Clinton writes, “Whether it was mere indifference or intentional fraud, Araminta’s mother and her progeny were cheated out of their freedom.” The lawyer also seems to have told Tubman that there was nothing she could practically do to challenge the Pattison heirs. Five dollars had purchased only a confirmation of injustice.

On September 17, 1849, Araminta, who now called herself Harriet, ran away to freedom, along with two of her brothers. Their owner, Eliza Brodess—Pattison’s granddaughter-in-law—had been making moves to sell them, and the fear was that the family would be broken up. Brodess put an ad in the local newspaper, offering a hundred-dollar reward each for “Minty,” Harry, and Ben. (The only extant copy of the ad was found in 2003, in a dumpster.) Almost immediately, Tubman began making trips back to Maryland, organizing the escapes of relatives, friends, and scores of other slaves, often just ahead of armed men pursuing them. On one trip, she discovered that her husband, John Tubman, who was free himself, was living with another woman; he had no interest in going north. He is a man who seems not to have known Tubman's worth.

“No slave who placed himself under her care, was ever arrested that I have heard of," Thomas Garrett, a Quaker abolitionist and storekeeper in Delaware, later wrote in a letter. Garrett’s role, often, was to get shoes and other supplies for the travellers. One day, he wrote, after Tubman had been out of touch for a few months, she came into the store and said that God had given her word that Garrett might be able to come up with some money. Garrett asked her, “How much does thee want?” She said, “About twenty-three dollars," a reply that he received with some wonder because, as it happened, he had received a five-pound note from a Scottish abolitionist who wanted to aid Tubman’s work. Garrett had exchanged the five, which, at the rates of the day, worked out to "twenty-four dollars and some odd cents,” and had the cash waiting for her—a twenty and change.

When the Civil War broke out, Tubman put her knowledge of the back routes of the South into the service of the United States Army, as a scout and a spy. Among other things, the intelligence she provided proved crucial in the capture of Jacksonville, Florida—a town named for a certain President who is now on the twenty, and who, in 1835, among other pro-slavery acts, gave Southern postmasters the authority to seize Abolitionist literature that passed through the mail. For what was hopefully not the last time, Tubman beat Jackson.

Secretary Lew, who can, technically, pick whatever portraits he wants, has responded to the arguments for putting a woman on the twenty by saying that the ten was the next in line for one of the periodic anti-counterfeiting redesigns all bills undergo. The twenty, however, will also need an upgrade soon. And there are four times as many twenties as tens in circulation. Given that women have waited a couple of centuries, it is worth getting this right. President Obama has the power to straighten this out—Lew would likely listen to him. Otherwise, there might be a need for a legislative move akin to a bill that Congress passed in February, 1899. At that point, Tubman, who was in her seventies, was living in upstate New York, largely on a pension she received as the widow of a Union soldier. (In 1869, she had married Nelson Davis, a bricklayer.) The amount of the pension paid to widows was eight dollars a month. In recognition of Tubman’s own military service, the bill, whose text included testimonials from three battlefield generals, raised her pension to twenty.

Tubman, meanwhile, had brought her parents to the North in 1857. She had made that trip in the summer, the riskiest season, after getting word that her father, Ben, who had been manumitted in middle age, was about to be arrested for harboring runaways. Ben and Rit’s position was already precarious, even though Ben, a few years before, had managed to persuade the Brodess heirs to let him purchase his wife's freedom. He paid twenty dollars.