In Southern Society, what characteristic defined those who were slaves?Was it based on skin color or on wealth?

In the ante-bellum South, slavery was a legal condition.
It was determined by one's status at birth. Unless one was imported, one was born into
the status of slavery; and the legal importation of slaves ended in 1808. Gradations of
color were common, as many slaves had at least one white parent. For that reason color
or wealth had no bearing on one's status. Because slaves were property, the owner
normally had a legal deed of title, except for those slaves who were born to slaves he
already owned, in which case he had the deed of title to the parent which normally
stated that the conveyance ncluded the offspring of the person titled. Legal titles to
slaves were typically recorded in public records. Some few slaves were amazingly light
complected, but this had no bearing on their legal status or their social standing.
Wealth was not normally an issue as slaves were not wealthy. They were normally allowed
to keep garden plots and raise some chickens and livestock and keep the money from the
sale of these items for their own use. Some managed to buy their freedom or the freedom
of their families in this fashion; but the accumulation of wealth was quite
anamolous.

The great exception was in the community of
freedmen. While slaves were grouped together with no social distinction, freedmen tended
to be rather snobbish based on gradation of color. Those who were lighter complected
considered themselves the social superiors of those who were of darker
color.

Your question raises an interesting point. In other
areas at other times, skin color and wealth were determinants; but in the U.S., it was a
matter of legal status, nothing more or less.