Where is the (Red) Line? How spatial misalignment of historical redlining maps impacts contemporary public health conclusions.
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Around the mid-1930s, the Home Owners’ Loan Corporation (HOLC) ranked urban neighborhoods from least to most desirable in terms of perceived mortgage stability based on racial and ethnic composition, documenting fine-scale spatial application of the structurally racist practice of redlining. Recent health and inequities research assigns historical redlining status (grades) from relatively small HOLC polygons to larger geopolitical boundaries (e.g., ZIP codes, census tracts). It is unclear, however, how such assignments (1) impact the interpretation of fine spatial scale redlining maps, (2) contribute to misclassification of redlining grade or other spatial covariates, (3) represent populations currently residing in historically redlined areas, and/or (4) impact effect estimates in epidemiologic studies that include redlining. We will present the results of ongoing analyses from multiple research programs that evaluate spatial misalignment in historical redlining research, compare historical redlining grades to contemporary redlining measures, and quantify the impact of spatial misalignment of historic redlining in epidemiologic analyses. We will address how historical redlining contributes to current public health priorities on health inequities research and provide recommendations for epidemiologists using historical and contemporary redlining data in public health research.