MS. DIANE REHMThanks for joining us. I'm Diane Rehm. President Andrew Jackson is getting bumped. His face will move to the back of the U.S. $20 bill. For the first time in a century, it will be a woman's face on the front of American paper currency and the first time ever that an African American will hold that spot. That woman is abolitionist Harriet Tubman. Treasury Secretary Jacob Lew made the announcement yesterday.

MS. DIANE REHMJoining us by phone from Atlanta to discuss the change, Isabel Wilkerson. She's a Pulitzer Prize-winning journalist and author of "The Warmth of Other Suns: The Epic Story of America's Great Migration." And Isabel Wilkerson, welcome back to "The Diane Rehm Show."

MS. ISABEL WILKERSONOh, thanks so much. Great to be here.

REHMIsabel, what went through your mind when you hear this news?

WILKERSONWell, you know, this is such a karmic moment in our country's history. You know, this announcement came a day after the one-year anniversary of the death of Freddie Gray, whose death, as we know, set off protests in Baltimore and we are still dealing with the effects of that case. We're in an age of Tamir Rice and Eric Garner and Black Lives Matter. And then, also I was recalling that we are not even a year out from the massacre at the Charleston church.

WILKERSONSo we are in this karmic moment and to have this announcement come and to think about a man who owned 150 enslaved people will now be replaced by a woman best known for freeing them, that is such a revolutionary moment for us at this time.

REHMIt surely is. Isabel, tell us a little about Harriet Tubman. American school children certainly learn about her in connection with the Underground Railroad. Tell us a little more about her.

WILKERSONWell, yes, so she was born into enslavement, into a family that was enslaved on the eastern shore of Maryland, which, at that time, was a slave state. And they believe -- we believe she was born around 1820. Of course, with many enslaved people, they could not say exactly when they were born. She, as a little girl, had been rented out from her family so she experienced a lot of heartbreak and homesickness because of that.

WILKERSONShe was whipped repeatedly and beaten repeatedly. In fact, at one point, she was -- at about 5 years old, she was told to watch over a baby, that was one of her jobs, and she was whipped every time the little baby cried. So she had a really hard life, obviously, as an enslaved person. And when she sought to escape, she once said that she sort of -- she channeled Patrick Henry, you might say, by saying that, I have a choice of doing one of two things.

WILKERSONI could either -- I have right to die or liberty. I have only two things that I can do, a right to liberty or to death and if I could not have one, I would have the other. And so it was at that time that in the 1940s that she -- sorry, the 1840s that she set out to free herself, escape to Philadelphia from the eastern shore of Maryland. And then, she went back. She went back and then ferried out or rescued hundreds of other enslaved people at great danger to herself and to them.

WILKERSONShe would often go in the wintertime because in the wintertime, the nights were longer and it would be a little bit safer, she felt, to be able to get them out. She was also know for being very strict on her efforts to get them out. She carried a gun and she was not afraid to say to them, now we are on our way out and if we're going to do this, you must follow my rules. And she would tell them, either you're gonna stay with me or you're gonna not endanger the rest of us.

WILKERSONAnd so she would get them out, often going as far as to Canada to get them to freedom.

REHMI gather she was the only woman to serve as a union spy during the civil war. What did she do?

WILKERSONShe actually was a scout and a spy for the union army and actually helped lead a raid into South Carolina. She was the first woman to lead an armed assault in the Civil War. She, in later life, as we know, became an ardent activist for women's suffrage and so she, at every stage of her life, was in the forefront of what we have come to believe as the American ideals of freedom, of liberty, of the right to be one's self in this new world.

WILKERSONAnd so, on many levels, she was at the forefront. And recall that she was an illiterate enslaved person. One of the tactics that she would use when she was on her way to freedom or freeing other people is that even though she couldn't read, she would know to hold up a newspaper as one of the ways to try to blend in as a presumed free person. She had an ingenious way of protecting herself and her charges as she was trying to get them to freedom.

WILKERSONAnd, of course, as you've said, she was the first woman to actually lead an assault during the Civil War.

REHMSo remind us of the process that lead to Treasury's decision to put her on the $20 bill. It was somewhat contentious.

WILKERSONWell, it is -- it continues to be contentious as we can see the response in social media and to people's conversations. We can see that this is still -- this is so revolutionary that to break from the tradition of what we are accustomed to seeing on our currency, that there's resistance from many people to seeing someone that does not look like the men that we've grown accustomed to seeing. On the other hand, there also are debates about what does this really mean in terms of how does this address the enduring issues of history that we're dealing with?

WILKERSONIn other words, having her there does not begin to make up for or redress the centuries of repression of people who did suffer for 246 years of enslavement and they're experiencing injustices to this day. So there's this question as to whether -- what does the represent and does this represent an easy fix, an easy suggestion, a gesture, a symbol of our having made more progress than actually may be the case on the ground? So this is something that is still very much in the public debate.

REHMYou said at the outset of this discussion that somehow this moment is karmic. Do you believe that given what you've said about what we've been through in Ferguson, Missouri, Staten Island, Chicago, do you think that the move to honor Harriet Tubman in this way will somehow be at least a small step toward healing?

WILKERSONWell, I absolutely believe that it will be. You know, whenever anyone breaks a $20 bill going forward, they will be reminded of the centrality of enslavement to the making of our country. And I think that for a symbolic measure on a daily basis, it's such a break from all that we have known. I think it will take some time for us to process what this really means for us, as a people, as a country.

REHMDo you think we'll also be reminded of the elements of the declaration of independence?

WILKERSONWell, I think that she lived up to and live the declaration of independence, even though it did not apply to her. And I think, for that reason, she represents, you know, a kind of inclusion of the forgotten people in our country. Ultimately, what she did freed not just the people who had been enslaved, but it kind of -- it freed the entire country of the scourge of the original sin that was the basis of the country's founding at the start.

WILKERSONAnd so, I think, for that reason, it extends far beyond our current sense of who we are. It helps to redefine who we are as a people and, of course, because the U.S. dollar goes all over the world, it's a message to the world of inclusion of people who had been marginalized for so long.

REHMI love the fact that there were more than 600,000 votes online and in person for a choice between or among 15 American women and that Harriet Tubman received the most votes. That must give you a great deal of satisfaction.

WILKERSONWell, it's a reminder that she, with so little -- I mean, she represented someone who had absolutely nothing, the very bottom of the hierarchy in our country and for her to rise to this level, you know. There's a story about her in which she had been hit by a two-pound weight as a teenager. An enslave, a slave owner, hit her with this weight, hit her head. It was meant for another enslaved person that was trying to escape, but she was the one who was hit.

WILKERSONAnd as a result of that, she ended up having seizures for the rest of her life, epilepsy, essentially. And at that time, the enslaver, the slave owner, said that she was not worth six pence after that. And now, she will be on the $20 bill. How is that for karma?

REHMHow is that for karma? Isabel Wilkerson, thank you so very much for being with us.

WILKERSONOh, thanks so much. It was a pleasure to be here.

REHMAll right. Thank you. And right after the break, we'll talk about some promising new developments in immunotherapy to treat cancer.