Established in the 1920s by University of Chicago sociologists conducting urban research, these zones represented moderately coherent social character across urban space at this generalized geographical scale. These so-called “community areas” have been widely used ever since as a convenient means of summarizing social and physical features of spatial units smaller than the city as a whole, with stable boundaries for the compilation of census data. From the beginning they only unevenly reflected the actual experience of community within the spaces, and over time many of them have become even less indicative of the perceptions of their residents, whose characteristics have shifted considerably due to migration. As ossified zones, they capture neither individual community identity nor the territorial reality of social groups. They remain useful, however, as subdivisions of city space that allow the study of change over time because of their stable boundaries.

Source: Newberry Library