By Hillary Busis
August 15, 2013 at 08:57 PM EDT

On August 28, 1963, hundreds of thousands of people flooded Washington, D.C., marching in one of the largest peaceful demonstrations in American history — and listening with bated breath to speeches and performances by figures like NAACP leader Roy Wilkins, gospel legend Mahalia Jackson, and, of course, Martin Luther King, Jr.

50 years later, celebrated author/illustrator — and wife/husband — team Andrea Davis Pinkney and Brian Pinkney are celebrating that milestone with a new picture book, Martin & Mahalia: His Words, Her Song. As the title implies, the story focuses on the friendship between Jackson and King, as well as the pair’s shared connections.

“Each of their personal stories kind of mirror each other,” Davis Pinkney explained to EW. “You see young Martin in the church, speaking the gospel, praying the gospel, seeking it, teaching it. And there’s Mahalia as a child — as it says, she sang the gospel, worked the gospel, led the gospel, spread the gospel. Those beautiful ribbons of harmony came together throughout the civil rights movement.”

For more on Jackson and King’s unique relationship and the book itself — not to mention a glimpse at one of Pinkney’s gorgeous painted illustrations — check out the rest of our interview below.

ENTERTAINMENT WEEKLY: Tell me about the genesis of this book. Obviously, the two of you have written several books about the civil rights movement — but what drew you to this particular story?

DAVIS PINKNEY: Well, I think the main reason is because a lot of folks didn’t realize that there was a friendship and a connection between Martin Luther King Jr. and Mahalia Jackson. And we didn’t know it until we happened upon that information through research. We know of them both separately, but the fact that they were friends and that each of their voices kind of led the civil rights movement forward  — we thought [that] was so intriguing.

PINKNEY: And that moment that they both performed together at the March on Washington, that was the key point: Mahalia started out singing, and then Martin Luther King delivered his speech after, inspired by  her.

DAVIS PINKNEY: August 28th, 1963, March on Washington. Those two voices come together so powerfully — her singing “I’ve Been ‘Buked and I’ve Been Scorned,” and that brass and butter contralto voice calming the crowd, making way for Martin. It was Mahalia Jackson who turned to her friend as he was speaking and said, “Tell them about your dream, Martin!”

I think about that. Had she not said that, would he have really ramped it up and began with “I Have a Dream” as we know it today? It somewhat mirrors our collaborative process as creative people, so we understand how it was that these two folks worked together.

What’s your collaborative process like?

DAVIS PINKNEY: What a lot of people don’t realize is that typically, authors and illustrators don’t know each other. They don’t meet; they don’t collaborate. But we’ve got this unique situation where I’m sharing the same box of cereal with the guy that’s illustrating my books.

PINKNEY: We’ve worked together so long, and Andra knows the way my mind works and what excites me. For example, she came up with the idea of having the dove in the book that would be this tool for children to follow — the dove of peace that leads the way as a beacon of hope throughout the book. So Andrea put those little things in the manuscript, and then I read it, and I was like “Okay, how do I bring this to life now?” One of the things that I used is the fact that Martin Luther King is always rendered in blues and greens, and Mahalia Jackson is always in reds. And then when they come together, it produces purple.

Do you share your work with your kids as you’re creating it?

PINKNEY: They’re really good at looking at covers.

DAVIS PINKNEY: They’re our best kind of test market, because they’ll be very honest. Sometimes my daughter or my son will read something and say, “you know, I like this here,” or “this doesn’t make sense,” or “how does that come together?” And I have to really rethink it.

The church plays a very important role in both Martin and Mahalia’s upbringing. Do you feel like the book has a religions message?

DAVIS PINKNEY: Not necessarily, no. I think it’s one of hope and triumph, and good feeling.

PINKNEY: And bringing people together and fellowshipping. Gospel and preaching were a way of communicating that brought people together, but that also carried on into the music that became the songs for the civil rights movement.

DAVIS PINKNEY: And a lot of scenes that are within the gospel tradition are things that we all feel. We all have faith in things, we all hope for things, we all move forward in fearlessness, and when you look at the 250,000 people that came together on that day, they were from all different walks of life, all faiths, all colors, all religions, all states, all backgrounds. And I think it’s astounding that this was before the days of Facebook, Twitter, email — the fact that that message got communicated and so many people showed up, I think it’s really incredible.

Do you have any plans for the march’s upcoming 50th anniversary?

DAVIS PINKNEY: Well, Brian, that’s your birthday.

PINKNEY: It’s actually my birthday, yeah. I turned two years old on [the day of] the March on Washington. So I will be celebrating my birthday and the march at the same time.

DAVIS PINKNEY: I celebrate more commemoratively. My father was at the March on Washington. My mom was all ready to accompany my father, but she couldn’t because she was eight and a half months pregnant with me. So I always listen to the speech, I always speak to my family. I love to hear their reminiscences about it, and that’s how we celebrate.