New Work with Census Data in GIS

NHGIS, one of the digital efforts of the Minnesota Population Center, is totally wonderful. Since I learned about it as a graduate student, it has been an essential source when I need demographic data from the U.S. Census and to help me think geospatially.

As a 20th century historian, and an urban historian in particular, I have run up against its limitations several times, which are really the limitations of the U.S. Census. The Census Bureau created the Census Tract framework and began implementing it in New York City with the 1900 census (augmenting and really replacing the Enumeration District). In 1910 it expanded to several other, slightly smaller cities and kept expanding to new cities every ten years. During the course of my masters thesis research on Ann Arbor, I was frustrated by the lack of Census Tract data before 1960 — the same goes for Berkeley in my book project.

In the course of my research on Austin, Texas, in the 1930s and 1940s, I realized that new digital methods and Census privacy law would allow me to break out of those limitations. Austin was tracted by the Census in 1940, but not in 1930. I realized that, because the 1930 manuscript Census — the individual-level records — are publicly available, I could plug them into 1940 Census Tracts and push the boundaries of the Census back in time. Here is how:


At least since Ken Jackson’s 1980 article in the Journal of Urban History, historians have been fascinated by the security maps created by the security maps created by the Home Ownership Loan Corporation and the process of state-sponsored segregation in finance, better known as redlining.

It has always surprised me that these maps, which are so plentiful in the National Archives, and so important in the analysis of urban historians, are not more widely available and have been digitized only on a very limited basis. I recently went to NARA II and RG 195 was chockablock with HOLC maps. I have digitized a handful that are of interest to me, and so I might as well make these available to the public at large, as they are in the public domain.

Click here for digital (HOLC MAPS). Generally high resolution.

HOLC map of Chicago's north side.

HOLC security map for south side of Chicago, 1939.

Not only do the HOLC files have a lot of maps, but the files for each city have real estate professionals’ analyses of each neighborhood in the city, regarding demographics such as race, ethnicity, work type, and income level, as well as housing information such as quality of construction and building types. Finally, for many cities HOLC had information on the home lending landscape, including the financial condition of major lenders and their lending profile. It is clear that this HOLC information was put to problematic purposes, but this is a very rich and robust set of information that historians should draw upon more frequently.

See also Robert Nelson’s page on Redlining Richmond at URichmond and the Digital Innovation Lab at UNC.

Evanston Map

The story of this Evanston map restoration is interesting on two counts. First, for the really great restoration process — taken from a curator’s experience with Japanese screen restoration. Second, for indicating how central Northwestern University was to the development of Evanston — in fact, they were major landlords and real estate players in their early years in the 19th century. The map itself is pretty great, as well.