The City of Chicago is divided into seventy-seven community areas. These areas are well-defined and static. Census data are tied to the community areas, and they serve as the basis for a variety of urban planning initiatives on both the local and regional levels.
The Social Science Research Committee at University of Chicago defined seventy-five community areas during the late 1920s. At the time, these community areas corresponded roughly to neighborhoods within the city. In the 1950s, with the city's annexations for O'Hare airport, a seventy-sixth community area was added. Other than the creation of the seventy-seventh community area in 1980 (by separating #77 Edgewater from #3 Uptown), boundaries have never been revised to reflect change but instead have been kept relatively stable to allow comparisons of these areas over time.
Today many of the community areas no longer correspond to any single neighborhood, and some community area names have fallen out of colloquial use. In many cases, the actual character of the community area is quite independent of that of the individual neighborhoods which comprise it.