Seems like it would make sense for her to put her Harry Potter manuscripts and related documents in some kind of archive where they can be properly preserved for future study and reference. Something like the British equivalent to the Library of Congress.
Has she done anything like this yet?
It seems as though they're still in her possession; other than a few items created specifically for auction, the only reference I can find to them being outside the possession of either Rowling or Bloomsbury, Inc. is when the manuscript of Harry Potter and the Philosopher's Stone was put on exhibit by the British Library in 2012.
However, the Harry Potter manuscripts are not part of the British Library's manuscript collection.
Rowling also posted pictures of some of her notes, including the original typescript of Philosopher's Stone, on her old website. Although that content was removed when Pottermore launched, the Harry Potter lexicon has archived it all.
If they end up anywhere, the most plausible location would be one of the United Kingdom's legal deposit libraries, of which there are 6:
But in practice, they could end up anywhere; J.R.R. Tolkien sold the original Lord of the Rings manuscripts to Marquette University, in Wisconsin of all places, in 1956. Of course, The Lord of the Rings wasn't the best-selling series of all time at that point, so the odds of Harry Potter winding up in one of the colonies is admittedly slim.
1 No, I'm not too proud to admit that I copy-and-pasted that
In a recent podcast interview Rowling has done, she was asked about her manuscripts and she said that she still has them all herself, and that she's considered donating them to a library but has held back mainly because she isn't comfortable with sharing them.
Simon Armitage: Is there a J.K. Rowling Archive somewhere of notebooks?
J.K. Rowling: No, no, no. It's all- I've got it all. I was talking to Ian Rankin about this the other day because he's donated his papers to the National library of Scotland? I think that's right.
Simon Armitage: But you've got all yours?
J.K. Rowling: But I've still got mine, yeah. I'm not even really sitting on them, it's just I don't know, I feel- I don't know what I'm going to do with any of it. Part of me thinks I'll just have a big bonfire.
Simon Armitage: Don't do that!
J.K. Rowling: No, I don't know. You know Nabokov said that awful thing about people exhibiting their first drafts, "it's like passing around samples of sputum". That's one of the quotations I've got on my writing wall and I do feel like it's passing around examples of sputum.
J.K. Rowling w/ Simon Armitage on The Poet Laureate..., BBC Website, Extended Version (24 July 2021) [22:28 - 23:11]
There are very few publicly released pages of Rowling's manuscripts. These tend to come from Rowling's old (pre-Pottermore) website, from a few early television interviews she did, and from a few pages that she lent to exhibitions.
In particular, as it may be relevant to where (if anywhere) she eventually chooses to donate her manuscripts, Rowling has previously lent some pages of manuscripts to exhibitions at the following four libraries and museums in the UK.
