The maps show a city quite different from the Chicago we know today. Population density in inner-city areas was generally much higher than it is now. Neighborhoods where immigrants from particular European countries made up a large proportion (though rarely a majority) of the population were still common. Owner-occupancy was associated largely with the single-family homes at the edge of the city (the condominium would come to Chicago in 1963). Chicago in the 1920s and 1930s was, like Chicago today, a city of great economic contrasts, but the geography was quite different. The only close-to-downtown neighborhood that was truly wealthy was a tiny sliver of the Gold Coast. Virtually all of the other neighborhoods around the Loop that have one by one been gentrified over the last fifty years--even Lincoln Park--were among the poorest places in the city in the 1920s and 1930s. Conversely, outer-city neighborhoods like South Shore and Rogers Park that now have their share of problems were among the wealthiest. The Burgess zones of concentric development can be seen in many aspects of Chicago geography in the 20s and 30s.
All of these maps (even those that say "Dept. of Sociology") were produced under the aegis of the Social Science Research Committee or its immediate predecessor, the Local Community Research Committee. Funded by the Laura Spelman Rockefeller Memorial, this entity particularly focused on supporting Chicago research. It is not clear who actually made the maps, although Ernest W. Burgess was definitely among those who administered the analysis of the data that underlay them. The maps were republished by the University of Chicago Press in Census Data of the City of Chicago, 1920 (1931), Census Data of the City of Chicago, 1930 (1933), and Census Data for the City of Chicago, 1934 (1934), although the versions used in the construction of this Web site are earlier editions published as separate pieces and held at the University of Chicago Map Collection."