A comprehensive analysis of 383 U.S. cities reveals a striking pattern: most have rings of isolation in suburban areas and segregated pockets of near the urban core, that are shaped by race, wealth, and proximity to downtown, finds a new study by UCL researchers.
Published in Nature Cities, the paper analyses the daily movements of people in cities right across America and found common patterns prevalent in every city analysed.
Using anonymised mobile phone SafeGraph GPS location data, researchers mapped the movement of millions of people over a four-year period, as they travelled from home neighbourhoods to places such as restaurants, shops, museums and hospitals. They combined this information with census block group data* on their home areas to estimate an individual’s likely median income and the demographic makeup of the area.
The authors revealed most U.S. cities have, "isolated" wealthier suburban neighbourhoods on the cities’ periphery, which are often majority white, and have few visitors from different socio-economic backgrounds. There are also other "segregated" poorer downtown areas, often majority non-white, where residents have few interactions with people of different backgrounds than them.
Lead author, PhD candidate Andrew Renninger (UCL Centre for Advanced Spatial Analysis), said: "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 U.S. cities are divided by invisible boundaries that shape who interacts with whom every single day."
This study is the first to look at this kind of data on what researchers call the ’mesoscale’ --the neighbourhood level between individual and city-wide analysis.
Andrew Renninger added: "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."
Researchers found that every city studied contained segregated pockets-areas where local amenities are mostly visited by people from the same neighbourhood or socio-economic background. While residents of these areas may travel elsewhere, outsiders rarely visit, limiting social diversity. These segregated zones are often poorer and predominantly non-white, with race and income strongly influencing integration. Amenities near downtown tend to attract more diverse visitors-except in majority non-white areas-while neighbourhoods farther from the centre are typically more isolated unless they are majority non-white.
Andrew Renninger added: "Much of this can be traced to historic discriminatory housing practices by federal, state or local governments that helped to create this segregation. The researchers point to areas such as South Central Los Angeles, South Side Chicago, and South Bronx in New York as such segregated pockets."
Around the suburban edges of most cities lie rings of isolation, where residents mainly interact with others of similar income or ethnicity. These communities tend to visit amenities that are themselves segregated, meaning their daily routines rarely reflect the diversity of the wider city. Such isolated rings are typically more affluent than the urban core.
Effect of COVID-19 pandemic
The timeframe of the analysis stretched from January 2019 through December 2022 providing insights into how the pandemic affected people’s movements. The team found that, expectedly, segregation and isolation peaked in April of 2020, during the pandemic, but levels largely returned to pre-pandemic norms by 2022, except for some cities like Boston and San Francisco, where isolation remained higher.
Co-author Professor Elsa Arcaute (UCL Centre for Advanced Spatial Analysis) 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; pushing all’activities to the neighbourhood scale risks reinforcing the very patterns of isolation we seek to avoid."
The researchers recommend that using these kinds of data, cities could use zoning and land use incentives to develop clusters of amenities in accessible areas between zones and invest in downtown to encourage greater social mixing.
Co-author Professor Neave O’Clery (UCL Centre for Advanced Spatial Analysis) 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."
* While the primary analysis focuses on income-based segregation, patterns strongly correlate with racial composition and historic discriminatory housing practices. Race was not directly measured; instead, demographic context was inferred from neighbourhood-level census data.
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