Cities are the central elements in spatial organization of regional, national, and supranational socioeconomies by virtue of the interregional organization in a total "ecological field" of the functions they perform.' In a specialized society economic activities are undertaken by design, or survive in the market place, at those locations which afford the greatest competitive advantage. Among these activities, those most efficiently performed in limited local concentrations provide the basic support for cities. The location theorist commonly classifies locally-concentrated economic activities into those which are raw material oriented, those located at points which are intermediate between raw materials and markets, and those which are market oriented.2 Raw material orientation includes direct exploitation of resources and the processing of raw materials, and its character is that of the developed resource endowment of different places. Activities in intermediate locations are usually of a processing kind, involved in intermediate and final processing and transformation of raw materials, and most frequently locate at some favorable spot on the transport network, such as an assembly point, a gateway, a break-of-bulk point, or a port. Market oriented activities may be secondary (for example, where there is a weight gain involved in the final processing of raw materials on intermediates prior to delivery), but are dominantly tertiary, concerned with the direct service of the consuming population through wholesale, retail, and service functions. The consuming population comprises the workers in the other specialized activities, of course, plus the local population supported by the tertiary trades. Thus, market orientation implies a location best suited to serve demands created by prior stages of the productive process. The three classic principles of urban location derive from the three types of locational orientation of economic activities: cities as the sites of specialized functions; cities as the expressions of the layout and character of transport networks; and cities as central places.3 All three principles, or some combination of them, may operate in the case of any particular city. However, whereas all cities