Library of Congress Control Number


August 13, 2022

Library of Congress Control Number (LCCN) - A number assigned to items cataloged by the Library of Congress used by US libraries to search for bibliographic records in databases and order catalog cards from the Library of Congress or other commercial suppliers.


The Library of Congress began printing its catalog cards in 1898, and from 1901 also distributed them. Each of them has a number that was used to identify and control catalog cards. It was called the Library of Congress Card Number. When the MARC format was introduced in the late 1960s, the number was still used, but was renamed Library of Congress Control Number (LCCN).


LCCN has the following structure: Prefix - May be empty or contain one to three lowercase letters of the alphabet. Year - these can be two (for pre-2000 LCCN) or four digits (for LCCN assigned from January 1, 2001). Serial number - has six digits. Supplement number - never used.

Assigning a number

US publishers can apply for an LCCN under Publisher Cataloging in Publication (PCIP). When submitting the application, the publisher receives an LCCN number and publish it in the book. This allows libraries to access the bibliographic record, but the publisher undertakes to send a free copy to the library collections. If the publisher fails to do so, he is banned from the program.

LCCN and Wikipedia

In the authoritative control module at the bottom of the Wikipedia page with a given entry, the subject of an article is identified by identifiers that come from 34 external sources. These are index entries and library catalogs. One of them is the LCCN, the Library of Congress Control Number.