Term in sociology indicating the level of Melanin required in the skin at which point a person is considered "Black." It can very across different cultures and regions. In some areas of the United States it takes very little pigment for a person to be considered black thus a low threshold, whereas other areas of Africa, the Caribbean, or South America require more pigment for a person to be considered "Black." It is important to watch that determining and utilizing this terminology does not become an ethnic filter.
That city considered me Black, they seem to have a lower melanin threshold.