Throwback Thursday!
This card sorter (from Gaylord) was used to sort catalog cards, first into smaller categories (like Dewey centuries or Library of Congress classes), and then those piles were sorted individually. In computer science, this is called a bucket sort. This particular card sorter has been modified to allow half-century buckets (e.g. 151-200 in one stack). We must have had a lot of cards to sort!