This chapter presents some generalizations reached in the study of the nine central business districts (CBDs). The foregoing details regarding the CBI method of CBD delimitation are intended as a basis for outlining comparable areas, with the ultimate goal of arriving at generalizations. The popular concept of CBD size is two-dimensional, and, of course, the district does occupy a certain gross area on the ground surface. The closer relationship of CBD size to corporate city population than to urbanized area population is difficult to explain. To most people the shape of the CBD is the outline that the district exhibits when depicted on a map. CBD shape was the basis for the work of George Hartman whose study was published in 1950. The multiplicity of actual shapes of central districts results from local conditions which are peculiar in detail to each district; it is these local conditions that produce variations from the idealized patterns.