Library of Congress Control Number

The Library of Congress Control Number (LCCN) is a serially-based system of numbering and cataloguing records in the United States Library of Congress.

• In its most basic form, the number includes the year of registration and a serial number. The year has two digits for 1898 to 2000, and four digits beginning in 2001. The three ambiguous years (1998-2000) are distinguished by the size of the serial number.
• Librarians all over the world use this unique identifier in the process of cataloging most books which have been published in the United States. It helps them access the correct cataloging data (known as a cataloging record), which the Library of Congress and third parties make available on the Web and through other media.

Note: If this service is purchased after your book has been published, additional fees may apply.