The effect of information and communication technologies on urban structure

Two innovations in the last century have changed dramatically the cost of communicating and transmitting information: The first is the widespread adoption of telephony; the second is the internet. We study the implications of these changes in ICT for urban structure. We find robust evidence that increases in the number of telephone lines per capita lead to a more concentrated distribution of city sizes and so correspondingly to more dispersion in the distribution of economic activity in space. The evidence on internet usage is more speculative, although it goes in the same direction. This empirical result is rationalized in a theoretical model.