What was the total prison population and prison population by race and gender from 1950 to 1975? I want to compare yearly prison population increases with civil rights victories.
There are two publications published by the United States Bureau of Justice which should be helpful for this question.
However, it is the National Archive of Criminal Justice Data that has what you want. Essentially, they can act as a repository for older information, which is good since the Bureau of Justice doesn't seem to have statistics on its page that go much farther back than 1975.
The two reports are:
Gender of Prisoners Admitted to State and Federal Institutions in the United States, 1926-1987
and
Race of Prisoners Admitted to State and Federal Institutions in the United States, 1926-1986
The above pages are descriptions of the studies. There are links on these pages to download the information. You will be told to login, which you can do anonymously. At this point, there are many options for what data you can download. Just to test, I went to Step 3 to download individual files. I was able to get the Codebooks, which are the .pdf files of the reports. Of course, it is sometimes nicer to have spreadsheets for analysing statistics. It is up to you to figure out what files and types of data you are comfortable with.