I haven't really researched the subject, but "local archives" appear to be subject to a lot of variation in the US.

It may be of interest that when I was nearing the end of my military service it was recommended that significant papers such as discharge orders should be "filed" as public records so that they would be "forever accessible" in case of loss of the originals. (The US Military has a "suspect record" for being able to retrieve information on service records, especially after discharge.)

The recommended method, probably fairly generally available anywhere in the US, was to take a notarized copy to the Clerk of the District or State Court, and request that it be filed. It should be given a "record number" and (sometimes) entered into a log of records, and the Court was obligated to preserve it (or "official facsimiles" of it) and to be able to retrieve it on valid request.

Since it would be mixed in with "Court records" which a judge could order "sealed" or that might otherwise have limited access, it was deemed important that you request it be filed as a "public record," since otherwise there might be significant "identification and validation" requirements for retrieval.

So far as I know, or have heard, only "paper documents" were eligible for filing in this way, although computers and "microfilm" were subsequently invented and new methods might permit other media in some places.

Unless the "document number" assigned by the clerk (and ideally, the exact date of filing) is kept safely accessible, retrieval of a specific document filed in this way may be difficult; but in most cases you do have some assurance that "it's there somewhere" as opposed to other places of storage where even that might be less certain. (According to acquaintances, at least one US Army Records Storage Warehouse burns to the ground about every week - since around 1890, based on US Gov't responses to requests for military sevice records.)

Some places appear to have "archive management agreements," often with Universities that have their own collections/archives, but in other places it seems to be left to the clerks who receive the material.

Some states require that all things filed be forwarded to State level archives, often with facsimiles retained locally, so sometimes a record can be found in either place.

In some places there may be other kinds of "archive repositories" but I don't know of others that are generally to be found.

Perhaps it's less complicated in other (outside the US) places?

John