Long-time series of racial maps with a time-invariant legend

Although there is significant literature on quantifying racial segregation in the US cities using numerical metrics, there is a lack of comprehensive studies that chronicle, over a long time, the evolution of the spatial distribution of racial groups from which segregation had arisen. Mapping multi-decades changes in racial geography of major US cities provide information on the evolution of spatial configuration of racial divides and, ultimately, provides insight into social processes that led to presently observed segregation. To fill this gap, we have developed and made freely available a set of GIS-compatible time series of racial maps featuring a time-invariant categorization of racial groups. These GIS-based maps cover 63 major cities in the US at the resolution of the census tract. Maps go back as far as the availability of the census allows, in some cases as far back as 1910. To make such map series possible, we needed to overcome changing categorizations of racial groups in past censuses and changes in the census tracts' boundaries. The paper explains our methodology and presents, as an example of temporal mapping, the case study for Cook County, IL (which contains the core of the present-day Chicago