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5th District Footprint

August 2018

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This issue of 5th District Footprint observes how racial segregation has changed in District countries from 1980 to 2016. 

Racial Segregation in the Fifth District: How Does Your County Compare?

In general, national measures of racial segregation between black and white residents indicate that the United States has slowly but steadily become less segregated over the past several decades.1 However, the legacy of slavery, de jure segregation and de facto segregationist policies like redlining2 perpetuate patterns of racial segregation. Against a backdrop of gradually increasing integration nationwide and ongoing research into the social and economic ramifications of racial segregation, this issue of 5th District Footprint asks: How has racial segregation changed in Fifth District counties from 1980 to 2016?3

Segregation fundamentally describes the degree to which two or more groups live separately within the same geographic area. This analysis focuses on segregation between black and white residents at the county level and uses a common measure of evenness called the Index of Dissimilarity (IOD) to quantify residential distribution.4 In essence, the IOD describes the percentage of white or black individuals who would need to move from their current census tract to one with an inverse racial composition for the census tracts in a select county to match the overall racial composition of the given county.5 For example, if a hypothetical county has a population that is half white and half black, but all census tracts are composed of one hundred percent either white or black residents, fifty percent of the county’s residents would need to relocate to a census tract with the opposite racial composition for the county to be fully integrated.6

The persistence of racial segregation has been linked to disparate outcomes in education, health and economic mobility. For example, higher black-white segregation in an area is linked to lower levels of bachelor’s degree attainment for both black and white residents, poorer health outcomes for black residents and fewer economic advancement opportunities for black residents.7 To effectively combat negative effects of segregation and to strengthen economic outcomes for all communities, it is essential to understand the geography of persistent racial segregation.

Nationwide, the IOD decreased from 75 in 1980 to 63 in 2016, meaning that as of 2016, 63 percent of black or white residents would need to relocate to a census tract with an inverse racial composition for there to be full integration in the United States. The IOD decreased in all Fifth District states and the District of Columbia from 1980 to 2016. As of 2016, the IOD ranged from 50 in North Carolina and Virginia to 70 in the District of Columbia.

On the map, counties that experienced an increase in segregation are shaded orange while those that experienced a decrease in segregation are shaded green. Counties that are shaded gray did not have sufficient census tract-level data in 1980 to calculate an IOD for the county. Those filled in with hash marks have fewer than 100 black residents as of 2016; calculating the IOD with such a small population may be misleading and so the data for those counties was excluded.

Change in Racial Segregation (Index of Dissimilarity) by County, 1980 to 2016

Source: IPUMS NHGIS 1980, University of Minnesota,; U.S. Census Bureau 2012-2016 American Community Survey, 5-Year Estimates.

Note: The Index of Dissimilarity is calculated such that higher values indicate greater racial segregation between black and white residents. The Index of Dissimilarity ranges from 0 (complete integration) to 100 (complete segregation). County level data are excluded if data was unavailable in 1980 or if there were fewer than 100 black residents in 2016.

Of the 15 Maryland counties for which data is available, ten counties experienced a decrease in segregation from 1980 to 2016 and five counties experienced an increase. Washington County – in the northwest part of the state – made the largest move toward increased integration with a -23 IOD decrease (71 to 48). Baltimore City had an IOD decrease of -10 (79 to 69) – so, as of 2016, 69 percent of Baltimore residents would need to move to a census tract with an inverse racial composition for the City to have full racial integration.

While 27 of the 52 North Carolina counties with data moved toward increased integration from 1980 to 2016, 25 counties experienced increased segregation. Chowan County – an eastern county in the state’s Tidewater region – had the largest IOD increase (and thus, the biggest move toward increased segregation) among all Fifth District counties at +33 (2 to 35).

Sixteen of the 24 South Carolina counties with data show a decrease in segregation from 1980 to 2016. As of 2016, county-level IODs ranged from 19 to 51, which is the smallest range among Fifth District states.

Of the 119 Virginia counties and independent cities with data available in both 1980 and 2016, 68 counties had an IOD decrease while 51 had an IOD increase. Martinsville City had the largest IOD decrease (and thus, the biggest move toward increased integration) among all Fifth District counties at -41 (75 to 34).

Due to data restrictions, change in IOD was calculated for just 14 of West Virginia’s 55 counties. Of these counties, eight moved toward increased integration while six moved toward increased segregation.


See e.g. Frey, William H. “Census shows modest declines in black-white segregation.” Brookings Institution The Avenue, December 2015; Acs, Gregory, Rolf Pendall, Mark Treskon and Amy Khare. “The Cost of Segregation: National Trends and the Case of Chicago, 1990-2010.” Urban Institute, March 2017.


Redlining refers to discriminatory lending practices that systematically limit lending based on race.


1980 is used as a comparison point because the 1970s and 1980s were generally a period of decreased racial tension in the United States. Data from 1980 is more broadly available at the county level than data from 1970. See e.g. McCarthy, Justin, “As a Major U.S. Problem, Race Relations Sharply Rises.” Gallup Social & Policy Issues, 2014.


The IOD presupposes that the county-level racial composition is indicative of integration. However, there may be segregation at the county level that makes the county’s black/white composition a skewed comparison point. A full discussion of the IOD and different segregation measures, as well as a visualization of the IOD can be found in “Racial and Ethnic Residential Segregation in the United States: 1980-2000” (2002).


A visualization of this example can be found on page 9 of “Racial and Ethnic Residential Segregation in the United States: 1980-2000” (2002).


See e.g. Acs, Pendall, Treskon and Khare, 2005; “2018 County Health Rankings Key Findings Report.” Robert Wood Johnson Foundation, March 2018; Chetty, Raj, Nathaniel Hendren, Maggie R. Jones and Sonya R. Porter. “Race and Economic Opportunity in the United States: An Intergenerational Perspective.” The Equality of Opportunity Project, March 2018.

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