Originally Posted by sirmaru
You can get there with this search routine as well and go deeper:
Kindle Edition>Prime Eligible>History>
You can change "History" to anything you want or just leave it off.
I just tried it and only found ONE history book and 20 total others. There used to be thousands there. It appears that Amazon is cutting down the numbers available for free borrowing.
That is the publisher's decision, not Amazon's.