The first library card catalog was created at Harvard in 1840. The cards were largely written by some of the first women employed in a library.

The first library card catalog was created at Harvard in 1840.

"Until the eighteenth century, when French revolutionaries took inventory of French libraries on the backs of confiscated playing cards, library catalogs were merely lists written or printed in books. But as book production dramatically increased, libraries looked for a more expandable way to organize their holdings. The Harvard Library’s answer to this problem, the card catalog, became the standard way to access library materials throughout the world for more than a century." Read more from the Harvard Library Blog

In 1877, one year after its founding, ALA voted standardize catalog card's sizes. They adopted the Harvard Library size as one of two standard options.

The earlier card catalogues used by Harvard were designed by Assistant Librarian Ezra Abbot and the retainer ran through this hole. Harvard was one of the first libraries to employ women. Beginning in May 1862 these women began writing information on catalog cards intended for the public card catalog, the first in the United States. In the first year they produced 35,762 hand written cards for the catalog." Read more from the Library History Buff