While I don’t doubt you, I feel the need to point out that the government has an amazing ability to lose things. I’ve been looking for a report from a particular government program for a number of years, and I even have the various catalog data about the report which the government put on the web several years ago. However, in contacting the various branches of government who should have copies of the thing, none of them have been able to find it. The last one response I got on the report, the researcher said that barring a miracle, they’d never be able to find it.
But being well-known - at least to those with the specialist interest - recognised as important, declassified, catalogued and accessible in the National Archives are already pretty much the best possible circumstances when worrying about safeguarding such material for posterity.