I did research into the 1956 budget, but I suspect the modern form of the US government was set by the early 1970s (Medicaid, Medicare).
Anything that wasn’t around by 1974 is probably not necessary.
And it is likely that only 10% of the government employees are actually doing work on things that need to be done. I have had to work with government employees for bout 40 years. I often had to write their monthly reports for them because they did not even understand what was going on.