postedThe SpineThe Rise and Fall of the Great Powers
Years ago I worked in the papers of various 1880-pre-1914 presidents, McKinley et al, and they all seemed to have given their papers to The Library of Congress. I think (but Prof. Gaddis can correct me here) that Hoover broke the tradition. Since then it has become increasingly ridiculous, and expensive (for the taxpayer as well as the researcher).
There is a Teutonic equivalent, produced by the vagaries of WWII. Before 1939 all official Prussian/German ministry archives were housed in Berlin (of course; just like the PRO). The dismantling of Nazi Germany led also to the splitting-up of those archives. The military/naval records (those not destroyed by Bomber Harris) ended up in Freiburg, the Foreign Ministry stuff in Bonn, the Colonial Office stuff in Potsdam, the Reich Chancellery archives in Merseburg, then the new Federal Archives was built in Frankfurt. Private papers, like Bismarck's, usually ended up at the country estate, with a bewildered great-grand-daughter wondering why anyone would want to see them (but also offering afternoon tea, in the library...) This explains why the archival listings in The Rise of the Anglo-German Antagonism are so much longer for the German side than the British.
Now, no president will have the acumen to avoid the vainglory of a Presidential Library, alas.