The urban core is the product of new work patterns enabled by modern telecommunications and transportation. With the advent of commuter rail, workers could live in comfortable quarters outside the overcrowded city center. Likewise, as industry came to rely on rail, production left the core for the periphery where railroads could interface with factory structures more freely.
Only management - together with commerce - remained, craving the superheated atmosphere of the city center and the potential for face-to-face, or alternatively, back room meetings. The telephone allowed the downtown office to keep in constant contact with workers in the periphery.