Urban Sprawl and Social Interaction Potential: an Empirical Analysis of Large Metropolitan Regions in the United States

This paper investigates the impact of urban spatial structure on the opportunities for people to participate in face‐to‐face activities. We make use of the Social Interaction Potential (SIP) metric, a tool to measure the average level of opportunity for people to engage in face‐to‐face activities given some basic constraints on their daily mobility patterns. Generally, this opportunity is a reflection of whether the urban spatial structure – a term that broadly applies to the spatial arrangement of land‐uses and the interactions between them – constrains or permits the ability for potential activity partners to be at the same place and time. In this paper, the SIP metric is applied to 42 metropolitan regions in the United States with populations over 1,000,000 people. These measurements are regressed against a set of indicators of urban sprawl to expose the relationship between spatial structure and SIP. The indicators are generated by a factor analysis of a large set of variables describing the scale, centrality and dispersion of land‐uses in addition to several other structural and infrastructure‐related variables. Cluster analysis is also used to organize the regions into similar groupings with respect to their structural characteristics and the level of SIP they provide. The findings indicate that social interaction potential is hampered by decentralization, fragmentation, and longer commutes in the largest metropolitan regions in the country. Interestingly, the negative effect of decentralization on SIP Efficiency is found to be nearly ten times stronger than that of fragmentation and nearly twenty times stronger than the effect of mean commuting duration.