Urban growth,transportation and the spatial dimension of the labour market: A note

Recently, Duranton and Turner estimated the impact of interstate highways on the average growth of US cities between 1983 and 2003. By estimating a structural model, one of their striking points is that increasing a city's initial stock of highways by 10 per cent leads to a 1.5 per cent positive respond of the city's employment over the sample period. This note mainly argues that their investigation leaves out potential spillovers of labour input from neighbouring growth centres/cities in the steady‐state directly implied by the open city assumption. More specifically, this contribution readily extends Duranton and Turner's work by a general equilibrium effect induced by the urban system's labour market fluctuations which is a direct consequence of the open city assumption.