The entire title is: The Warmth of Other Suns: The Epic Story of America's Great Migration.
This book covers the roughly 60 years in the last century where blacks went North and West to get out of the dangerous South. She uses three (real) people from different places, to different places, who did different things, etc., to show the variations of what happened in the Migration.
Her writing of the stories adds context, for example, between 1889-1929, a black was hanged or burned every four days. During the migration, Detroit's black population grew from 1.47% to 44%. The turn of the 21st century has more blacks in Chicago than the entire state of Mississippi. One of the people of whom she writes, Dr. Foster, knows Ray Charles and is mocked in Hide nor Hair (which is not accurate about Foster).
The book has 84 pages of context and 538 pages of stories. The context is quite thorough: Notes of Methodology, Afterword, Acknowledgments, Notes, Index, and Permissions: Acknowledgments.
It is long, but the stories were very interesting and the context giving more info. I recommend it.