World's Largest Collection of Overdue Notices on Postal Cards?

The United States Post Office Department introduced postal cards with pre-printed postage in the United States in 1873. Libraries were quick to take advantage of postal cards and used them for a multitude of purposes. One of the most common purposes especially for public libraries was to notify library users of overdue books and other library materials. Postal cards are generally ephemeral in nature and overdue book notices are especially ephemeral. After all, how many people would want to preserve an overdue book notice. In my efforts to collect postal librariana I have managed to accumulate a collection of over a hundred postal cards that have been used as overdue notices. It may well be the largest collection of overdue notices in the world. The impressiveness of that accomplishment is somewhat tempered by the fact that almost half of them were sent to a single address in Dubuque, Iowa. The dates of the overdue notices in my collection go from 1873 to the 1980s. This post includes a few overdue notices from my collection. More are shown on a page at my Library History Buff website. I have a previous blog posts on the oldest overdue notice in my collection and the second oldest.

Third oldest notice. Mailed May, 1875 by Lawrence (MA) Public Library.