About this map
Once almost completely white, Chicago is becoming increasingly diverse, with minority populations growing by the decades and white populations steadily shrinking.
This map shows how the city’s racial demographics have changed each decade from 1930 to 2010. The map also shows which areas have been more popular with certain groups and how that has changed or stayed the same over time. African American communities on Chicago’s South Side, for instance, didn’t always outnumber white communities. And Latino communities are constantly spreading.
How it works
The map dynamically plots points using demographic and geographic data collected by the U.S. Census Bureau and obtained from the National Historical Geographic Information System (NGIS). First, files outlining census tract regions across the country were downloaded and converted into data tables. These boundary tables were then paired with demographic data tables showing the racial make-up of each tract.
Using the joined tables, Google maps API plots a point representing each demographic in a random location within the boundaries of the appropriate district. For this map, only Cook County tracts are used.
The U.S. Census Bureau constantly changes its criteria for racial data. Some racial categories that show up in one decade’s map may not show up in another. Data in 1940, for instance, only distinguish whites from non-whites, and during this census, Mexican Americans were counted as white.
The map uses only census demographics found through the National Historical Geographic Information System. Some groups listed as individual races on actual census forms may have been re-categorized or renamed in the available data tables.
The Latino ethnic group is currently distinguished from racial groups, so Latino populations are plotted on a separate map. NHGIS data tables for Latino populations only date back to 1970.
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Give the map time to load the several thousand map points.