In 1996, Isabel Wilkerson stood in front of a group of half-interested Chicago Transit Authority retirees—all elderly, most black, and many, she guessed, originally from Mississippi. Her pitch went something like this:

I’m working on a book about the Great Migration of black Americans to the North and West, and looking for people who moved up from the South to escape Jim Crow, to follow a factory job, to chase a better life for their families. They must have stories and be willing to tell them.

The resulting book, The Warmth of Other Suns: The Epic Story of America’s Great Migration— winner of the National Book Critics Circle Award—is also Wilkerson’s journey: the story of a daughter of migrants seeking to understand her forebears’ need for fulfillment—for a chance, in the words of twentieth-century African American writer Richard Wright, to “respond to the warmth of other suns and, perhaps, to bloom.”

For half of her adult life, Wilkerson, a Pulitzer Prize-winning reporter and a professor of journalism, has been working to bring the story of America’s black migrants to life—and to embed that history in America’s cultural consciousness. She first learned her own family’s story in bits and pieces: finding photos of her mother as a young woman in Washington, D.C., just moved from Georgia and basking in her newfound freedom; listening to her father, who left Virginia for the capital, tell tales of his time as a Tuskegee Airman.

Wilkerson’s interest in the subject grew as early newspaper gigs took her to Los Angeles, New York, and Detroit, and then to the Chicago bureau of The New York Times. Everywhere, she found veterans of the Great Migration. Her observations—for example, the large number of black Chicagoans she interviewed who were born in ­Mississippi—fed her desire to learn more. “I knew that it was a national phenomenon, because as a national correspondent I had approached it at every turn,” she says.

In 1994, a Pulitzer Prize for feature writing made Wilkerson the first black journalist to win an individual reporting award at that level, and inspired her to undertake a book-length exploration of the Great Migration. It was, she says, the tipping point for an idea that “had been marinating in me for a long time.”

She spent the next 15 years collecting oral histories and doing original and archival research, tying together historical, demographic, and economic studies of the Great Migration with a survey of its vast cultural impact on African American art, literature, and identity.

“She’s like a heat-seeking missile,” says Lou Ureneck, a professor and former chair of journalism, of Wilkerson’s undaunted search for a way to tell the story of two million lives. “She’s a woman with a mission.”

In the course of her research, Wilkerson learned that demographers, sociologists, and economists had long studied the diaspora of black Southerners and its consequences—including labor shortages in the South and white flight in Northern cities—as a logistical “problem.” Journalists, meanwhile, “only came in when there was a bombing” of a black home or church, she says. A more thorough account of the migration and its effects meant weaving many threads into a much larger whole.

Wilkerson came to view her subjects more as immigrants than migrants, the term that stuck after Southern blacks moved north for factory jobs during World War I. She saw it in how they adjusted (or didn’t) to the cultures of their new cities, and in how, by sheer ­determination, they worked harder, sought more education, and raised more stable families than their native-born black counterparts in the North and West—evidence that countered traditional wisdom on Southern blacks, who were assumed to have brought drugs and crime to America’s cities. But mostly, she says, she saw it in their journeys: like Ellis Islanders or even modern refugees, some African Americans traveled great distances in extraordinarily dangerous or inhospitable conditions to escape the South.

“The only way for people in this country to stop taking the movement of individuals in the Great Migration for granted is to see how dramatic it was,” Wilkerson says. “There was no backup plan. This was the biggest decision of their lives, and it had to work.”

Wilkerson hopes that readers will take away much more from The Warmth of Other Suns than her subjects’ experiences. “I would love for people to go to the oldest member of their family and talk with them about how they got here,” she says. “Everybody came from somewhere else.”

Watch a video of Wilkerson discussing The Warmth of Other Suns