Restoring Continuity: An Aggregative, Open-Source Methodology for Harmonizing Disparate Census Tracts Across Time

Urban analysis often relies on census or census-like survey data, but the redesign of census tract layers often breaks historical comparability, thereby hampering longitudinal studies at the local scale. In this article, we propose an automated methodology for making census tracts comparable through the construction of a graph, using spatial join operations and non-spatial id comparisons. We adopt an aggregative heuristic to minimize the impact of the matching process on analytical possibilities. To validate the proposed methodology, we deploy it to match the most recent Brazilian censuses for the São Paulo, Vitória, and Recife metropolitan regions, as well as for the Brazilian Federal District. We also test our implementation for New York City and Buenos Aires. We then evaluate the results against available gold standard data and alternative metrics, concluding with a discussion of potential improvements. Our implementation produces comparability files efficiently and has the potential to enable studies that would otherwise be impractical.