ABSTRACT
Perhaps the clearest aspect of the structural evolution of metropolitan areas is the decentralization of both jobs and housing. During some periods, US central cities have grown at a lower rate than their suburbs; in others, the decline has been in absolute numbers. The overall trend is fairly strong, particularly over the past century:
Many questions remain regarding the consequences of this pattern of decentralization and deconcentration or, to use a broader term, sprawl. Much of the debate concerns environmental resource issues, such as the excess conversion of open land to urban uses and pollution problems associated with overdependence on cars. The potential social impacts are also widely discussed. For example, one of Putnam's (2000) 'sprawl' explanations for a decline in US social capital is that the suburban commute leaves less time and energy for social interaction.
