As an integrated database, the includes 3.2 million catalog records from an earlier database. These catalog records, primarily for books and serials cataloged between 1898 and 1980, are being edited to comply with current cataloging standards and to reflect contemporary language and usage. The legend [from old catalog] indicates that the headings may deviate from current Library of Congress cataloging policy.
The Library of Congress both catalogs newly published books as well as shares that descriptive information with other libraries. For many decades, starting in 1901, the format the Library used to share that information was the catalog card. The process of creating, printing, organizing, storing and distributing those millions of cards took hundreds of staff at the Library of Congress and vast spaces, such as the ones shown below. (See all of those thousands of boxes on the shelves and tables? Full of catalog cards printed at the Library.)
The Library of Congress Cataloging Distribution Service continues to provide cataloging information to libraries in various ways, but its last catalog card was printed in 1997. Just last month, , marking the end of an era.
The Library of Congress Online Catalog contains approximately 14 million records representing books, serials, computer files, manuscripts, cartographic materials, music, sound recordings, and visual materials in the Library’s collections.