Interestingly while at the National Archives this week I asked some of the employees if there was anything avialable on the internet along the lines of the "Preliminary Inventories" you must use to have records retrieved when you visit. They were not aware of anything, however they were very helpful and I got everything I was looking for.
I got home and looked for some related info on the web and a site with a sort of "survey" I'd call it, of National Archives info popped up. It has a different organization, within the various record groups, than that used to retrieve records, so even with the entire website at hand, you'd still need to look up specific "Entries" within the record groups to access the information.
One of the primary Record Groups I use is RG 156, the Records of the Office of the Chief of Ordnance, U.S. Army.
The webpage that has the "survey" of it (and all the other holdings) is at:
You can click on each blue number and get more detailed information. Or you can click on this to get a bit different slice of the info (which you get from clicking on the small icon of a computer on the upper right of their page)
I now have my own copy of the inch-thick, double-sided "preliminary inventory" of RG156, which lists each "entry" by number, title, physical size, period of coverage (often the period of coverage seems broader than justified by actual holdings I've seen.)
The RG number, the "entry" number, and a few words describing it are what the Archives workers in the "Finding Aids" room require you to fill out on the retrieval form once you've located what you want in the "preliminary inventory." I'm not sure why the Archives doesn't post the "preliminary inventories" online, but like anything else, it is probably a cost/manpower issue.
If you are planning to visit the National Archives in Washington DC, plan to arrive early in the day, because the Archives has recently revised its internal schedule.
The last "pull" of the day from the stacks is at 2:30, meaning you may not get the records you requested until 3:15 or so, and the Archives closes at 5PM sharp most days. The lodging and dining costs in Washington DC motivate most visiting researchers to complete their work so as to minimize the number of local overnight stays.
If anyone is visiting for the first time and wants some pointers from someone who has spent hundreds of hours there, I'd be happy to help.
I've seen great improvements the Archives' customer service, particularly several years ago or whenever they streamlined the entire process of locating information by establishing the "finding aids" room right on the ground floor. No longer do you have to allocate a bare minimum of one-half day to merely locating and requesting the information, but if you are visiting for the very first time, that's still a good estimate.
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