TITLE: Data Tuesday: Chicago Demographics 1940-2020
SUBTITLE: 9 Maps for 9 Decades
AUTHOR: Peter Banks
DATE: 2025-07-02
URL: https://peterbanks.org/essays/data-tuesday-chicago-demographics
SOURCE: https://peteribanks.substack.com/p/data-tuesday-chicago-demographics

Today will be the first article in what I, currently, intend to be a weekly article series I’ll be calling “Data Tuesday”1. The plan for these is to keep the editorializing to a minimum and instead just present some interesting data that I’ve discovered or created.

This week I will be showing granular demographic maps from Cook County between 1940 and 2020. I’ve stylistically followed UVA’s racial dot map(which I believe is now depreciated) and am using census data taken from NGHIS. If there is general interest, I will post the code I used to generate these graphics; however, I have done nothing particularly sophisticated.

The data will be reported at the census tract level, the most granular I could find regular data for, and each dot represents 100 people of a certain race.

If I do not say otherwise, you should assume the following mapping for these graphics. 

Blue: White PeopleGreen: Black PeopleRed: Asian PeopleYellow: Other People

They will also be shown in a key.

Note: 

The categories that were reported changed regularly. I will report the groupings that NGHIS gave me, but this does make intertemporal comparison more difficult. 

The data I worked with did not separate out Hispanic people for any of the years. I may return in the future with data that includes ethnicity in addition to race—the American census is weird—and update these graphics.

1940:

For this year, the census reported two groups: White and and Nonwhite. Additionally, the data doesn’t appear to cover the entirety of Cook County and focuses only on the “core”.

1950:

This year, the census reported White, Black, and Other.

1960:

1960’s categories are identical to 1950.

1970:

In addition to the prior categories, the dataset I used to construct this—“nhgis0005_ds95_1970_tract”—included a breakdown for various Asian ethnicities such as “Japanese,” “Chinese,” etc., which I have consolidated under “Asian.”

1980:

This census had a marker for Native American, which I have included in Other. Looking at the map, it appears to pick up quite a few Hispanic people, although this isn’t possible to know with certainty and is based only on the scale of the Native population in Chicago and their geographic location.

1990:

I’ve made the choice to group Asian and Pacific Islanders together into a single group I call “Asian” for readability. Once again I also chose to combine Native and Other.

2000:

This census introduces the ability for people to choose more than one race, which is reported as “two or more races.” I leave this as its own category.

2010:

2000, 2010, and 2020 all have the same categories in the data which makes reporting them easy. 

2020:

Finally, the most recent census!

Let me know if anything jumps out to you!

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1Hopefully I’ll release it not at 10:30pm on future Tuesday’s but realistically these will come out at random times.
