Library of Congress Control Number (LCCN)
In the world of library science, organizing millions of volumes requires a precise system of identification. The Library of Congress Control Number (LCCN) is a serially based numbering system used to identify cataloged records within the Library of Congress in the United States. Unlike classification systems that categorize a book's subject matter, the LCCN serves as a unique identifier for the record itself.
It is important to distinguish the LCCN from the Library of Congress Classification (LCC). While the LCC describes the contents and subject of a book to determine its place on a shelf, the LCCN is simply a tracking number for the bibliographic record.
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Key Facts
- Purpose: Acts as a unique identifier for bibliographic records, not a subject classification.
- Origin: Established in 1898, originally known as the Library of Congress Card Number.
- Global Use: Used by librarians worldwide to locate accurate cataloging data for U.S. publications.
- Structure: Consists of a year and a six-digit serial number.
- Digital Access: The LCCN Permalink service provides stable URLs for non-suppressed records.
The History of Centralized Cataloging
The LCCN system began in 1898. At its inception, it was referred to as the Library of Congress Card Number (or Library of Congress Catalog Card Number). During this era, the Library of Congress practiced centralized cataloging, where they created physical cards containing bibliographic information and sold duplicate sets to other libraries.
Each set of cards was assigned a serial number to ensure they could be identified and tracked. While modern libraries have transitioned to electronic storage and sharing of bibliographic data, the need for a unique identifier remains. The LCCN continues to fulfill this role, allowing librarians to access the correct cataloging record—the detailed data describing a publication—via the web and other media.
In February 2008, the Library of Congress introduced the LCCN Permalink service. This tool provides a stable URL for any LCCN that has not been suppressed. However, an assigned LCCN will not be associated with a record if the item was never added to the collection or was subsequently removed.
Understanding the LCCN Format
The LCCN is composed of two primary elements: a year and a serial number.
The Year Component
The format of the year varies based on the date of the record:
- 1898 to 2000: Represented by two digits.
- 2001 to Present: Represented by four digits.
Certain historical nuances exist within this system. For example, the years 1898, 1899, and 1900 are distinguished by the size of their serial numbers. Additionally, records starting with "7" may contain a check digit due to an experimental system implemented between 1969 and 1972.
The Serial Number Component
The serial number consists of six digits. Modern standards require leading zeros to pad the number to its full length, though older records may appear shorter because this padding was added more recently. While a hyphen is often used to separate the year from the serial number, it is optional; the Library of Congress currently advises publishers to omit the hyphen.
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LCCN Summary Table
| Feature | Details |
|---|---|
| Established | 1898 |
| Primary Function | Unique identification of catalog records |
| Year Format | 2 digits (1898-2000); 4 digits (2001+) |
| Serial Format | 6 digits (including leading zeros) |
| Permalink Service | Launched February 2008 |
Frequently Asked Questions
Is the LCCN the same as the LCC?
No. The LCCN (Control Number) is a serial identifier for the bibliographic record, whereas the LCC (Classification) is a system used to categorize the book's content by subject.
Does the LCCN tell you what a book is about?
No, the LCCN is not related to the contents of the book; it is simply a number used to identify the record in the library's database.
Why do some older LCCNs have fewer than six digits in the serial section?
Leading zeros were added to the format more recently. Older works were recorded without this padding, resulting in shorter codes.
What is the LCCN Permalink service?
Introduced in 2008, it is a service that provides a stable, permanent URL for LCCNs that are active and not suppressed in the system.
Should publishers include a hyphen in the LCCN?
No, the Library of Congress has instructed publishers not to include the hyphen between the year and the serial number.