Segregation Indices




To determine the extent of any segregation based on race or national origin in the eight studied communities, the ICRC calculated community-specific segregation indices. These indices of dissimilarity show the relative proportion of a minority group that would have to move to achieve an even residential distribution within the community. For example, the 1990 segregation index for Dubuque is .51 for African Americans. This means that 51% of the African Americans living in Dubuque would have to move to different neighborhoods or census tracts to make Dubuque non segregated.

For a community to have an index of 0 (indicating no segregation), the minority population percentages for the city as a whole and each census tract would have to be equal. For example, if 15% of a city population is African American, then each census tract would have to have a 15% African American population to achieve a segregation-free, 0 index.

One of the most commonly-used methods or formulas to determine the level of segregation within a community, and the one used by the ICRC, is the index of dissimilarity as described by Douglas Massey, Professor of Sociology at the University of Pennsylvania, in his 1995 article, "The Changing Structure of Black-White Segregation in the U.S.," Social Science Quarterly.

The index is calculated as:

n

I = SUM .5 | (bi/B) - (wi/W)|

i=1

 

bi = # minority group members in census tract I

wi = # whites in census tract I

B = # minority group members in the community

W = # white sin the community

n = # census tracts

The index can vary from 0 to 1. A score of 0 means that no segregation exists in the community and a score of 1 means that the community is totally segregated.

The ICRC calculated segregation indices for each of the eight communities based on 1960, 1970, and 1990 census data. The ICRC also calculated an expanded index for each community based on 1990 data which includes suburban census tracts outside official city limits. For example, West Des Moines was included in the expanded index for Des Moines and Marion was included in the expanded index for Cedar Rapids.

 

Segregation Indices

 

    1960 1970 1990 1990E~
Cedar Falls          
African American .51 .47 .16 N/A
Asian American .47 * .19 N/A
Latino * .41 .21 N/A
Cedar Rapids          
  African American * .63 .47 .50
  Asian American * * .36 .34
Latino * .55 .20 .21
Council Bluffs          
  African American .55 .65 .47 .75
  Asian American .33 * .47 .36
  Latino * .52 .39 .45
Davenport          
  African American .70 .75 .46 .58
  Asian American .47 * .42 .42
  Latino * .44 .30 .32
Des Moines          
  African American .77 .72 .62 .63
  Asian American .44 * .44 .38
  Latino * .50 .28 .31
Dubuque          
  African American * .57 .51 N/A
  Asian American * * .56 N/A
  Latino * .68 .29 N/A
Iowa City          
  African American * * .26 .26
  Asian American * * .39 .38
  Latino * * .26 .25
Sioux City          
  African American .74 .71 .53 .54
  Asian American .55 * .49 .47
  Latino * .54 .45 .43
Waterloo          
  African American .76 .80 .66 N/A
  Asian American .60 * .49 N/A
  Latino * .53 .29 N/A
Waterloo/Cedar Falls          
  African American .90 .94 .82 N/A
  Asian American .74 * .69 N/A
  Latino * .94 .36 N/A

 

~The 1990E index includes the census data from the suburbs surrounding the communities in the study. The suburbs added include: Omaha (Council Bluffs); Sergeant Bluff (Sioux City); Windsor Heights, Clive, Urbandale and West Des Moines (Des Moines); Coralville (Iowa City); Marion and Hiawatha (Cedar Rapids); Bettendorf, Moline, South Moline and Rock Island (Davenport).

Note: 1960 data for Iowa City, Cedar Rapids and Dubuque is unavailable. The 1960 census for Iowa did not include the Latino population. The 1970 census did not include the Asian American population. 1970 data for Iowa City is unavailable.


SEGREGATION INDICES

MIDWEST CITIES

    1990
Wichita, Kansas    
  African American .67
  Asian American .51
  Latino .37
Omaha, Nebraska    
  African American .71
  Asian American .40
  Latino .40
St. Louis, Missouri    
  African American .80
  Asian American .44
  Latino .29

 

Note: 1990 Index of Dissimilarity for Midwest Cities as reported by USA Today (November 11, 1991). The USA Today author used data provided by Professor Massey.



Lending report main page