The number of minorities serving in legislatures, councils, and governing boards varies greatly across regions of the country and across levels of government. For example, on the national level, there are more black members of Congress in the North than in the South, while at the local level more blacks serve in the South than in the North.

This paper accounts for the variation in black representation primarily as an interaction of the concentration of blacks (in both raw population numbers and in population percentages) and the size of the constituency unit. We show that electoral geography is the single most important element in explaining variations in black representation in government by section and by type of office.

We are not claiming, however, that electoral geography is the only major influence on minority electoral success. We recognize that election method is critical; in particular, it is well known that at-large elections produce fewer minority representatives than other systems, independent of the effects of geography. But we show that election method does not vary as greatly by region as does electoral geography. Thus, regional differences in black representation across levels of government can best be explained by making sense of electoral geography.

Complete article:

Bernard Grofman and Lisa Handley. Black Representation: Making Sense of Electoral Geography at Different Levels of Government. Legislative Studies Quarterly Vol. 14, No. 2 (May, 1989), pp. 265-279.