It’s hard to imagine our world today without Michelle Obama, without Spike Lee, without a Motown, without an Oprah. A new book details how the great migration of African-Americans away from the South led to some of the greats of our time, including basketball legend Bill Russell.

Pulitzer Prize-winning author Isabel Wilkerson profiles the NBA star in The Warmth of Other Suns. The book addresses his life growing up in Monroe, Louisiana and his family’s journey to Oakland, California as a kid in the mid-1940s.

“We never considered a migration — that’s a modern term. We considered it immigration, because we left one country to go to another country, completely different culture, not knowing what to expect,” Russell said on The Last Word. He appeared on the show alongside Isabel Wilkerson to talk about the book.

“My father had an encounter with his boss, and he decided to leave over a pay raise,” he said. “He told my father he couldn’t give him a pay raise because he couldn’t pay one of the ‘N’-words as much as he paid the white boys. So my father decided to leave.”

Russell says it was a big transition to go from an integrated school to “sitting in class with these white kids.” He said, “That was a completely foreign situation to me, because my mother, in particular, always kept white people away from me. She would always keep me away from them, because she said she didn’t know what they would do.”

It took Wilkerson 15 years to conduct research for the book. "It’s unimaginable to think what might have happened if we had not had the opportunity to really understand the affect of six million African-Americans leaving the Jim Crow South, a caste system which had held them fast in a particular place, and defecting,” says Wilkerson.

Check out Lawrence O’Donnell's full interview with Russell and Wilkerson below.