My local library was much denser as a child as well.

Except that's because the library was tiny. The denseness was a necessity and the library was constantly trying to get rid of books to make room for newer books.

Thankfully they eventually replaced that tiny library with a much bigger one. And the one we live near now is also much bigger and much better. I think the kids section of the library is probably double the size of the entire library we had growing up, with more books as well.