Spatio-temporal changes in racial segregation and diversity in large US cities from 1990 to 2020: a visual data analysis

Urban populations in large US cities exhibit racial and ethnic diversity, yet they remain residentially segregated. The examination of temporal trends in segregation and diversity is crucial for sociologists and urban planners. In this study, we investigate the spatio-temporal changes in segregation and diversity across 61 major US cities, utilizing data from four US Censuses conducted between 1990 and 2020. Unlike previous studies, our approach relies on visual data analysis, enabling us to capture the overarching changes in racial coresidence during this period. We employ four distinct perspectives – geographical, temporal, groups evolution, and desegregation scale limit – to visualize and analyze the data. Geographical analysis uncovers a decrease in regional disparities in urban diversity and segregation since 1990, as urban racial integration extends beyond West Coast and Southwestern cities to encompass the entire US. Through temporal analysis, we observe a general trend of rapidly increasing diversity and gradual reduction in segregation, albeit with varying rates across different cities. Groups evolution analysis reveals that cities grouped based on their diversity and segregation metrics in 1990 follow the overall trend toward larger diversity and smaller segregation while preserving group’s coherence but not their distinctiveness. Finally, the desegregation scale limit perspective suggests that, on average, over the 1990 to 2020 period, the desegregation scale has started to subceed the lower limit of the census block. By employing these diverse analytical perspectives, our study provides a comprehensive understanding of the changes in racial segregation and diversity within US cities over the past three decades.