It helps to have really smart friends who also love books. And since we only have a few days left in February, I hope you'll use this list well beyond the confines of February.
By the way, my informal call for other books that should be on a list like this one led to the question, "What counts as modern?" To me, a modern black history book is one that was published in the past 20 years and is frequently overlooked in stories about black literature that are passed around during Black History Month.
Here are some of the titles that came up:
Makes Me Wanna Holler: A Young Black Man in America by Nathan McCall
(And I would add that anyone interested in black masculinity and its challenges also read Cool Pose : The Dilemmas of Black Manhood in America and Manchild in the Promised Land.)
To 'Joy My Freedom: Southern Black Women's Lives and Labors after the Civil War by Tera W. Hunter
Race Rebels : Culture, Politics, and the Black Working Class by Robin D.G. Kelley
Ella Baker and the Black Freedom Movement: A Radical Democratic Vision (Gender and American Culture) by Barbara Ransby
The Cross of Redemption: Uncollected Writings (Vintage International Original) by James Baldwin
Words of Fire: An Anthology of African-American Feminist Thought Edited by Beverly Guy-Sheftall (For related books, specifically anthologies, I also recommend The Black Woman: An Anthology and Daughters of Africa)
Call & Response: The Riverside Anthology of the African American Literary Tradition Edited by Patricia Liggins Hill
Blues Legacies and Black Feminism: Gertrude "Ma" Rainey, Bessie Smith, and Billie Holiday by Angela Davis
Ida: A Sword Among Lions by Paula J. Giddings
I would be remiss if I didn't recommend Taylor Branch's Parting the Waters, the first in a trilogy of books about America during the King Years.