Thanks for the website Mapping Inequality: Redlining in New Deal America, I have better copies of the Sacramento redlining map, which was produced in 1937 by the Federal Home Loan Bank Board and the Home Owners Loan Corporation (HOLC). These were government sanctioned zonings meant to guide banks to only loan to certain kinds of people in certain areas. Specifically, higher income white people.Though the official endorsement of the federal government eventually ended, the practice continued into the 1970s, and is with us still today. The best book on it is The Color of Law: A Forgotten History of How Our Government Segregated America by Richard Rothstein, which I highly recommend.
I had seen this map before, most likely from the posts of Bill Burg, but had not seen a high quality version, and had never found the GIS data. In 1937, Sacramento was a pretty small city, not going south past Land Park or north past Del Paso Heights, so the maps only cover a tiny part of what is today Sacramento. But as the city grew into other areas, the same practice redlining continued.
The first map below is the ArcGIS version, the second a scan of the original 1937 map.