Blacks were not always at the back. I have found some early
directories where people were listed alphabetically,  and
some people were listed as Free Person of Color, or maybe
their color was or was'nt listed. Some "colors" were
debateable I guess . And in some cases I don't think the
people really cared. So, check all listings. And from what
I've seen if you were black and had a business it did not
say 'black owned'.  And I recall a directory in late 1800
with the blacks listed in the front of the directory. So,
don't take anything for granted.

I have some people that changed color from year to year!

I would suggest going to an LDS Church Library and
requesting the microfilm of the Richland City Directories. I
have only seen directories for the cities of Columbia and
Charleston which began in the late 1700's and early 1800's.
I would imagine that smaller towns did have city/town
directories, but I have not found much in the way of them in
my SC research. The smaller the town the less likely the
chance they had a directory (in my opinion).

Perhaps there are some Historical Societies in those areas
that could tell you if in fact they did have directories, or
not. The town libraries may be a place to look.

God Bless the Orderly person that decided to make a list of
all the people in town!

Janet