Here is a link to info on Georgetown County: http://www.rootsweb.ancestry.com/~scgeorge/
I visited the Historical Society in Georgetown and found a treasure-trove of history books for sale. So contacting the historical society of your county might be worthwhile.
If anyone has contacts with black families in Georgetown County that go back to the 1920s, please let me know. I have some photos but the only identification is "Old Sam." (My grandfather Burr Callis was superintendent at Nightingale Hall.)