Does anybody have a complete list of locations for the three National Scholastics? Steve Immitt’s history of the National High School is sufficient for my purposes, but I can’t find anything like it for the other two Nationals.
You could track part of the information yourself by looking at the “past events crosstables” on this website back to 1991. Before that you would have to look up TLAs and post-tournament articles in Chess Life & Review and Chess Life backwards to the middle 1960’s. I don’t recall seeing any articles that gave a historical perspective of these tournaments the way Steve Immitt has done for the US High School Championship.
IIRC, some of the annual yearbook editions of Chess Life list past winners of the national scholastics (at least, the “major” ones, anyway). I believe I’ve seen some of those lists include, among other things, the location of the event. That might be a place to start.
It is easier to track through a player. Not every organizer calls it the same thing (i.e. one organizer would use the 1995 National JHS, another the National Junior High School), so when you search, it takes a while to find them all.
It is tedious searching, but you would need to look at the TLAs in the Chess Life Annuals or specific magazines from Feb. to May from Chess Life & Review and Chess Life to find details (site, time controls, sections, etc.) on the tournaments. To see results, or at least articles about the tournaments, you would need to sift through the May to July issues. Most of the tournaments have been held in the March to May period. Yes, computer search is even more frustrating as the names of the tournaments are not consistent from year to year.
If you have access to the magazines through a club or a pack rat who has kept everything since the dawn of man, it should only take about minute or two a magazine to find what you want. Roughly 10 minutes per year of the magazines or 100 minutes per decade. 5 decades. Maybe 7 or 8 hours to peruse through old magazines just to find what you are looking for. Then there is the reading and collating of the material. The computer search back to 1991 might take longer than that as the information is scattered among a number of different names. Depending on how OCD a researcher is, it could take 3 to 4 days to find what you want, that is, if you have the piles of materials available to read. That is a minimum estimate of the work involved.
We all look forward to your articles on these tournaments. 
They would add to our historical knowledge of these events.
It took me about two weeks of doing the above to locate, compile and write the material for the National High School Championship for the years 1969-1997. The Chess Life coverage of the USCF Nationals was much more abbreviated in the 1980’s than it is now, and some of the stories were hard to find. Fortunately I was able to interview the organizer of the early events personally, and that helped fill in some of the blanks.
I would have liked to have done a much more comprehensive and thorough article including many more games and human interest slants. However, I was also trying organize the 1998 National High School Championship in May at the same time. I had originally undertaken the tournament history report mainly to have something interesting for the players to read inside the tournament program book, and to try and give the players a sense of the history of their event and a connection to their predecessors. Looking back I think this turned out to be the most rewarding part of organizing the whole tournament!