Library of Congress Control Number


August 13, 2022

The Library of Congress Control Number (LCCN) is an identifier for a cataloged record assigned by the Library of Congress. The LCCN, originally "Library of Congress Catalog Card Number", is the database identifier (record number) of an entry in the American national bibliography including the authority data; it is listed in field 010 (and 001) of the MARC files. From 1901 until the introduction of the MARC service, American libraries could order catalog cards from the Library of Congress under this number, which is why these numbers are often found in the imprint of American books (cf. Cataloging in Publication today). The system has been in use since 1898. It is independent of the content of a book and should not be confused with the Library of Congress Classification (LCC). The Library of Congress Authorities (LCAuth), a counterpart to the Common Authority File (GND), also use the structure of the LCCN.


In its current form, which was introduced in 2001, the identifier consists of a two-digit alphabetical prefix, which is only used for authority data (persons and subject headings), followed by the four-digit year and a six-digit ordinal number. The latter is often shortened for better readability and separated with divis. Examples: ␣␣␣92022183 (92-22183) Knapp: Elliptic curves (book) ␣␣2002024184 (2002-024184) Marker: Model theory (book) n␣␣50036535 (n50-36535) Guy Davenport (Person) n␣␣94112934 (n94-112934) Barack Obama (Person) no2008168642 (no2008-168642) United States. President (2009-: Obama) (person) sh␣85092242 (sh85-92242) Noncommutative rings (Keyword)The MARC prefix identifies the creator of the record. For individuals, "n" is for the Library of Congress, "nb" for the British Library, "no" for the Online Computer Library Center (OCLC), "nr" for the Research Libraries Information Network (RLIN), and "ns" for the Sky River database. Until the year 2000, only a two-digit year was used. For the ambiguous years 1998, 1999, and 2000, the trailing serial numbers start at a specified offset. A special feature applies to numbers beginning with a 7 because of an aborted experiment from 1969 to 1972. The sequential numbers within a year consist of six digits with leading zeros. The hyphen inserted in the number is optional and should no longer be used, per recent Library of Congress guidance.

See also

Library of Congress Subject Headings (thesaurus for keywording)

Web Links

Structure of the LC Control Number Search the catalog of The Library of Congress Library of Congress Authorities WorldCat Identities; Search mask for authors and their associated Library of Congress Control Number.

Individual proofs