Reason for Including as Additional Measure:
Although most overtly discriminatory policies and practices promoting segregation, such as separate schools or seating on public transportation or in restaurants based on race, have been illegal for decades, segregation caused by structural, institutional, and individual racism still exists in many parts of the country. The removal of discriminatory policies and practices has impacted acts of racism, but has had little effect on structural racism, like residential segregation, resulting in lingering structural inequalities. Although this area of research is gaining interest, structural forms of racism and their relationship to health inequities remain under-studied.
Residential segregation remains prevalent in many areas of the country and may influence both personal and community well-being. Residential segregation of Blacks and Whites is considered to be a fundamental cause of health disparities in the US and has been linked to poor health outcomes, including mortality, a wide variety of reproductive, infectious, and chronic diseases, and other adverse conditions.[1,2] Structural racism is also linked to poor-quality housing and disproportionate exposure to environmental toxins. Individuals living in segregated neighborhoods often experience increased violence, reduced educational and employment opportunities, limited access to quality health care and restrictions to upward mobility.[2,3]
Residential Segregation – Black/White is an Index
Racial/ethnic residential segregation refers to the degree to which two or more groups live separately from one another in a geographic area. The index of dissimilarity is a demographic measure of the evenness with which two groups (Black and White residents, in this case) are distributed across the component geographic areas (census tracts, in this case) that make up a larger area (counties, in this case).
The residential segregation index ranges from 0 (complete integration) to 100 (complete segregation). The index score can be interpreted as the percentage of either Black or White residents that would have to move to different geographic areas in order to produce a distribution that matches that of the larger area.
Some Data are Suppressed
A missing value is reported for counties with Black population less than 100 in the time frame.
The Black/White residential segregation measure is only available for counties with a Black population of at least 100 (applies to approximately 65% of US counties).
This measure is a reflection of racial and not ethnic discrimination. People identifying as Hispanic can be included in either the Black or White groups.
This measure can be used to track progress with some caveats. It is important to note that the estimate provided in the County Health Rankings covers a 5-year period. However, in most counties, it is relatively simple to obtain single year estimates from the resource included below.
Years of Data Used
American Community Survey, 5-year estimates
The American Community Survey (ACS) is a nationwide survey designed to provide communities with a fresh look at how they are changing. It is a critical element in the Census Bureau's reengineered decennial census program. The ACS collects and produces population and housing information every year instead of every ten years, and publishes both one-year and five-year estimates. The County Health Rankings use American Community Survey data to obtain measures of social and economic factors.
 Gee G, Ford C. Structural racism and health inequities: Old issues, new directions. Du Bois Review. 2011;8:115-132.
 Kramer MR, Hogue CR. Is segregation bad for your health? Epidemiol. Rev. 2009;31:178-194.
 Bailey ZD, Krieger N, Agénor M, Graves J, Linos N, Bassett MT. Structural racism and health inequities in the USA: Evidence and interventions. Lancet. 2017;389:1453-1463.
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