ABSTRACT
In 1841 Kohl investigated the relation between cities and the natural and cultural environment, paying particular attention to the effect of transport routes on the location of urban centers. Periodically in the past century the location and distribution of cities and settlements have been studied. A theoretical framework for study of the distribution of settlements is provided by the work of Walter Christaller. The essence of the theory is that a certain amount of productive land supports an urban center. The center exists because essential services must be performed for the surrounding land. Thus the primary factor explaining Chicago is the productivity of the Middle West; location at the southern end of Lake Michigan is a secondary factor. Christaller points out that Cologne is really the commercial center for the Ruhr industrial district even though it is outside the Ruhr area. Even in mountain areas centrality is a more important factor than topography in fixing the distribution of settlements.
