I know that " The 1910 census was the first for which the Census Bureau tabulated tract data." I am interested in census tract level data for race (white, white foreign-born, negro) in California (Los Angeles County) from 1910 to 1940s.
I see that, for some areas, this is available, but not for California. Is that due to 1) a characteristic of the source data, or 2) have researchers done detailed work in some areas, but not others?
First, I see that NHGIS does have tract-level race data for a few areas in California for 1930 and 1940.
To get a quick idea of tract data coverage, you can use the Census Tract links in the GIS File Availability table. Those documents show our coverage of tract boundary data by year, and we almost always have some table data for any area where we have boundaries… though not necessarily a race table. The documents show that we have 1930 tract data for LA and 1940 tract data for four counties around LA and SF-Oakland.
To find tract-level race tables for these years, I went to the NHGIS Data Finder and selected filters for Geographic Level = Census Tract and Topic = Race. I then opened the Datasets filter to see which datasets have tract and race data. This 1930 dataset has some:
1930_tPop_Misc Population Data [Tracts: Selected Areas in CA, MD, MA, MO, NY & TN]
And this 1940 dataset has some:
1940_tPH_Major Population & Housing Data [Tracts & NY Health Areas: Major Cities & Surrounds]
I selected and downloaded race tables from both of those datasets, and they do include data for the CA counties indicated above.
Of course, that still doesn’t get you all the way back to 1910, so to answer your specific question: the historical limits on NHGIS tract data are mainly a limitation of the source data. To my knowledge, for these years, we’ve added all published U.S. census tract data to NHGIS.
This is very helpful, thank you. 1930 by census tract will help!
1910 (and, hopefully, 1920) by county will be fine, and it helps me to know I am not missing something. Thank you!