I recommend the good essay by the late Gary B. Mills, "Shades of Ambiguity: Comparing Antebellum Free People of color in 'Anglo' Alabama and 'Latin' Louisiana," in Samuel C. Hyde, ed., Plain Folk of the South Revisited (Baton Rouge: Louisiana State University Press, 1997). The book is in print in paperback, and is available at many larger libraries.

For comments on another topic covered in the same essay, see the link below.

There is a tantalizing reference in Mills' essay to a database of Alabama Free Persons of Color, apparently compiled from court records in every available Alabama county. I had enquired of one of Dr. Mills' students about the whereabouts of this database and if it is accessible to researchers. He said I would need to contact Dr. Mills' widow. I have not yet done so.