Based on the author's childhood in the 1930 is Alabama, where she watched her father defend people in the local court it was published during the Civil Rights Movement "Those of us who stood up for civil rights were much encouraged by the book because in a very skilful and subtle way it addressed itself for justice." - Rev.Butts (who was a civil rights campaginer).
You could also try 'Roll of Thunder here by Cry' by Mildred D. Taylor which tells the story of a black girl in Mississippi in the 1930s.