The decentralising metropolis: Economic diversity and commuting in the US suburbs

This paper investigates historical changes in economic structure and the spatial distribution of jobs and commuting patterns during a period of consolidating suburban decentralisation in US cities. The analysis of selected US metropolitan areas is based on data drawn from the 1980 and 1990 PUMS (public use microdata samples). First, the paper compares changes in employment composition between regions and between two geographical sub-divisions in each of the metropolitan areas: the suburb and the central city. A diversity index is then measured for suburbs and central cities and an intertemporal comparison is made. Finally, changes in travel characteristics are discussed and analysed by industrial sector and geographical sub-division. The analysis shows a strong growth of suburban cities compared with central cities in each region, increased urbanisation economies in suburban cities and the dominance of suburb-to-suburb commuting. The historical pattern gives urban analysts and planners in Europe and elsewhere much to think about: in particular, the self-reinforcing nature of suburban agglomeration economies, the influence of growing suburban employment centres on commute patterns, the growth of centre-to-suburb commutes and the dominance of suburb-to-suburb commutes; and the ability of cities to reshape themselves as individual firms and households adopt strategies that lower the costs of transacting labour, services and all manner of commodities.