A major current effort is to replicate the initial 1880 process of creating geocoded city maps for 1930 and 1940 for the largest 79 cities (based on 1940 population).  61 of these cities have been studied at the census tract level for 1940 using a limited set of variables originally transcribed by Donald and Elizabeth Mullen Bogue (see ICPSR data file 2930).  Tract boundaries have been disseminated through the National Historical GIS Project (Minnesota Population Center).  Now that 100% microdata are available for these years, it is possible to aggregate data to the enumeration district (ED) level, which is finer than census tracts, for all data that were gathered by the Census in both 1930 and 1940.  The current project is supervised by John Logan, and it is has included several doctoral students and postdoctoral research associates at Brown University over the last few years.  It has benefited from support from the professional staff of Brown’s initiative in Spatial Structures in the Social Sciences and financial assistance from NICHD and NSF. 

There are more relevant sources of information about the layout of cities in these years than were available for the 1880 project. Major steps have included development of a historically accurate street grid for the cities in 1930 and 1940, determining census block and ED boundaries, reconciling the many ways that addresses and street names were recorded by enumerators and transcribed by Ancestry.com with the street maps, and finally geocoding the addresses of all households.  A key resource that is widely used by genealogists and that greatly facilitated our work is the website stevemorse.org developed by Stephen P. Morse and Joel Weintraub. 

Full documentation of procedures used in this mapping ae being published in a book chapter: John R. Logan and Weiwei Zhang. 2017. “Developing GIS Maps for U.S. Cities in 1930 and 1940” In Don Lafreniere, Ian Gregory, and Don Debats (editors), The Routledge Handbook of Spatial History. Routledge: UK.