Andrew Renninger, PhD candidate at the Bartlett Centre for Advanced Spatial Analysis (CASA), has published research in Nature Cities examining segregation patterns across American cities. Co-authored with Professor Elsa Arcaute and Professor Neave O'Clery, the paper analyses daily movement patterns to reveal how race, income and geography shape urban social mixing.
Using anonymised mobile phone GPS data from SafeGraph, researchers tracked millions of people over four years (January 2019–December 2022) as they moved between homes and amenities, including restaurants, shops, museums and hospitals. Combined with census data on income and demographics, the analysis revealed two distinct patterns across all 383 cities studied.
Most cities have isolated, wealthier suburban neighbourhoods on their periphery, often majority-white, with few visitors from different socio-economic backgrounds. Downtown areas contain segregated pockets, often majority non-white and poorer, where residents have limited interactions with people from different backgrounds.
Cities are supposed to be melting pots – places where people from different backgrounds mix, share ideas and create opportunities. That’s what makes cities engines of innovation and wealth. But our research shows that many US cities are divided by invisible boundaries that shape who interacts with whom every single day.
Understanding neighbourhood-level patterns
This is the first study to examine such data at the mesoscale – the neighbourhood level between individual and city-wide analysis.
Andrew said, "Tracking these networks is important because a lack of connections between residents of a neighbourhood and the wider city and broader economy can fuel inequality in creating a disadvantage for those residents while also limiting growth for the whole city."
The research identifies how segregated pockets emerge where local amenities are visited primarily by people from the same neighbourhood or socio-economic background. These zones are often poorer and predominantly non-white, with race and income strongly influencing integration. Areas such as South Central Los Angeles, South Side Chicago and South Bronx exemplify such patterns, which can be traced to historic discriminatory housing practices.
Impact of COVID-19
Segregation and isolation peaked in April 2020 during the pandemic but largely returned to pre-pandemic levels by 2022, except in cities like Boston and San Francisco where isolation remained higher.
Prof Elsa Arcaute said: "COVID-19 effectively created a large-scale social experiment in which more localised living revealed its potential downsides, namely increased segregation and reduced exposure to diversity. It reveals that not all aspects of daily life can – or should – be localised."
Policy implications
The researchers recommend that cities use zoning and land use incentives to develop accessible amenity clusters between zones and invest in downtown areas to encourage social mixing.
Prof Neave O'Clery said: "Our research offers policymakers and planners valuable insights for developing amenities around cities that can encourage greater diversity and social mixing. By encouraging more strategic development, it can help isolated residents better connect with the broader community and economy, reducing inequality."
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