ABSTRACT
Well in excess of 90 per cent of the United States economic activity is concentrated in that small fraction of the nation's land surface which we call urban. This tremendous concentration of productive and consumption activity exists by virtue of the extraordinary conditions of viability of the urban organism. One set of these conditions has to do with the anatomy of the city—its arrangement in space in ways to assure interaction among the multitude of consuming and producing activities that compose the urban economy. This is the set of conditions on which I intend to concentrate—the network of interaction which I call communication and in which I include both the exchange of information and the physical movement of goods and people.
