This paper studies an urban growth model where learning through personal contacts could be more effective in a denser locale, whereas the effectiveness of learning through impersonal means of communications depends principally on the technology of communications rather than on the locale in...

While aggregate data do not show the investment echoes predicted by vintage-capital models, echoes arise in rates of entry and exit of firms at the industry level. Moreover, industries where prices decline rapidly experience early 'shakeouts'. The relation emerges naturally in a vintage-capital...