An exploration of Chicago Demographics

Project three for Geol-340 used Chicago demographic data from 1990 and 2000.  It was titled “For Richer or Poorer in Chicago” from our Making Spatial Decisions using GIS workbook.  The scenario given is that a University department wants to understand that movement of different White, Hispanic and Black populations in Chicago, as well as the relationship to wealth and changes in segregation.  I was given a series of maps to make, and my job was to interpret them and display the data to show clearly the interesting elements of them.  These maps would be for academics and researchers in sociology or other social science fields.

As shown in Fig. 1, I observed patterns in both Chicago and the surrounding Cook county, and started with overall population.  I calculated population per square mile in order to see population density of each tract.  Showing overall population of each tract would not be as telling, as a suburban tract with a very large area may have more people than a smaller urban tract, but be less dense.  As shown in Fig. 1, most people live within the city limits.  The vast majority of the census tracks in the suburbs have under 15,000 people per square mile.  Southern Chicago is also less populated and the far northeast region.

Fig. 1: Cook County Population per Square Mile


I then compared the race and ethnicity of Cook County and Chicago between 1990 and 2000.  Comparing the data visually shows little changes.  I normalized the data for black, hispanic and white populations by the data pop1990 and pop2000 respectively, to calculate percents of each population per track instead of just total amount of people within each demographic. You could have data showing way more black people in one census tract than another, but that could simply be because one of the tracts is especially large area wise or especially densely populated. If you normalize the data with total population you get a percent, and can see how many black people proportionally make up each tract/neighborhood/region/etc.  There is significantly larger percent of black people in the southern part of Chicago and the city and a gap with only 0-20 percent Black populations in the far se region, the western part of the city and county, and the northern part of the city and county.  There are significantly smaller populations of Hispanic people than black and white people in Chicago, and about an equal deficit of Hispanic people as black people in the suburban regions of the county. The highest percent populations of Hispanic people inChicago are in the central parts of the city and the far South East. They do not match up very well with the densest black populations or White Populations. The White populations as seen in the maps is pretty much inversely related to black populations. It looks like someone took the same map but switched the dark and light colors. The vast majority of the outer Chicago region of the county is 81- 100% White. North and SW Chicago are also very white. Like with the % population black and Hispanic, white populations did not shift dramatically between 1990 and 2000. Looking at google maps, the suburbs have the most parks and the White people. The largest Hispanic populations are pretty close to the river. Black and Hispanic Populations are much more densely populated in the urban regions.

Fig. 2: Percentages for White, Black and Hispanic populations

Chicago 3

I then calculated the diversity index for each census tract.  As shown in Fig. 3, the clusters of high diversity are in the northwest and southern regions of the county. In 2000 the northwest, east and southern regions have higher diversity.  The highest diversity indexes appear in the middle eastern region of Chicago.  The southwest region is not very diverse.  Looking at Fig. 4, the suburbs are less diverse.  The tracts with high diversity indexes have more similar percentages of white and black populations, but still generally have less hispanic and asian populations than white and black.  The diversity indezes in this county seem dominantly controlled by the level of segregation between white and black people, as the other populations remain relatively small all around for the most part.


Fig. 3 and 4: Diversity Index Maps



Looking at the mean centers for black and hispanic populations (fig. 5), both shift over time.  The mean center for black people shifts south and the mean center for hispanics shift southwest.  The directional distribution for both groups becomes slightly larger, and the Hispanic distribution shifts West and the black distribution shifts south.  Hispanic and Black populations are distributing over larger areas and are overlapping more with one another.  This shows a slight decrease in segregation.

Fig. 5: Mean Center and Spatial Distribution of Hispanic and Black Populations


Going back to diversity indexes, this 3D display helps further visualize the diversity of the different tracks.  The darker the color, going from yellow to red, the higher the diversity index.  These colors clump large groups of indexes together.  The height of each census tract shows the number for the diversity indexes by each census tract.  The higher the block, the higher the diversity.  This helps differentiate different tracts that have been clumped together by color.

FIg. 6: 3D Diversity Indexes

Chicago DI

I next created a 2D map showing the median house value of each tract. The lowest median value was $9,999 and the highest was $1,000,000.  The highest value houses appear to be in the north and SW of Chicago, but the distribution of house values over all is rather random looking, as seen in Fig. 7.  On the histogram the Y axis represents the number of houses and the x axis represents the median price of houses.  Fig. 7’s graph shows a downward curve, where the more expensive the house, the less houses there are in that price range.

Fig. 7: Median House Value


I then created a double variable extruded map, as shown in Fig. 8 that shows diversity indexes and median house value.  the darker the color of the tract, the higher the median house value is. The taller the building, the higher the diversity index.

Fig. 8: Median Household Value vs. Diversity Index 3D map


The last part of this lab was to create 3D maps for Hispanic, White and Black populations. Fig. 9 shows White populations, Fig. 10 shows Black populations, and Fig. 11 shows Hispanic populations. Looking at Fig. 10, the areas with high percentages of black people have lower median house Values.  The areas with higher percentages of white people (Fig. 9) have a widely dispersed range of median household values.  In the north, especially be, there seems to be richer, whiter neighborhoods, and in the SW there appear to be poorer, whiter neighborhoods.  The areas densely populated with Hispanic people have lower household values, as seen in Fig. 11.

Fig. 9: White Populations vs. Median Household Value in Chicago



Fig. 10: Black Populations vs. Median Household Value in Chicago



Fig. 11: Hispanic Populations vs. Median Household Value in Chicago.


Other variables that might help us understand Chicago’s diversity include evaluating individually other races, such as Native American populations, and the mean centers for populations other than black and hispanic ones.  Another important variable is average household income, which is different from average house value.  Average income more directly relates to economic status than the home value of the neighborhoods.  For instance, a family may be stuck in a house they can no longer comfortable afford due to change in income and unable to sell their home.  Alternatively, a wealthy family may choose to live in a cheaper house and neighborhood and spend their money on other luxuries.  Both average household value and income are important variables, and using both could get more to the heart of Chicago’s economic demographics.

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