National Getis-Ord Gi* statistics for select populations; 1990-2019

Local Getis-Ord Gi* statistics were calculated as a measure of residential segregation. Measures were calculated at the census tract level based on the proportion of non-Hispanic White, non-Hispanic Black, non-Hispanic Asian [and Pacific Islander for 1990 and 2000 census], Hispanic, and immigrant persons (regardless of country of origin; 2008-2012 only) per census tract. Gi* statistics are Z-scores that compare the proportion of the population in the focal tract and its neighboring tracts to the average proportion of a larger geographic unit. For the majority of tracts, the larger geographic unit was the Core-Based Statistical Area (CBSA) these tracts belonged to. The county was used as the larger unit for tracts that fell outside the boundaries of a CBSA. Data for the measures were obtained from the IPUMS National Historical Geographic Information System (NHGIS) data finder. Data were downloaded for the 1990 and 2000 census, and the 2006-2009, 2008-2012 (Immigrant segregation only), 2010-2014, and 2015-2019 5-year American Community Survey (ACS) estimates. Geographically standardized time series tables were used for 1990 and 2000 census data. All other ACS data were standardized to 2010 census tract boundaries. G*statistics were calculated using both Rook and Queen conceptualization of spatial relationships. With Rook contiguity, neighbors are determined by those that share a common edge only, while Queen contiguity neighbors are those that share both an edge or a "corner" (common vertex). See detailed documentation for further details.