The Invisible Line
by Daniel j Sharfstein may provide good background reading.

"The WALLS trace their roots to a wealthy plantation owner in Rockingham, North Carolina. Stephen Wall never married but he had children with three of his slaves. In the 1830s and 1840s he freed his children and sent them to Ohio to be raised by radical Quaker abolitionists.
He bought land for them, generally supported their education at places like Oberlin College and willed them money. Interestingly he kept their mothers in bondage. The children became ardent abolitionists, served in the Union Army and worked with the Freedmen's Bureau.
After he War, several moved to Washington, D.C., where they fought for civil rights, women's rights and raised their families to expect nothing less than equality. BUT as Reconstruction gave way to Jim Crow, their children disappeared into the white world."

Seventies queries:

Are there any special records in North Carolina that would help me in assisting this family search? All help is greatly appreciated. I will be starting in Winston-Salem, NC looking for any family with the surname of Wall