Library of Congress

Library of Congress is one of the major providers of Authority Records.

Library of Congress is responsible for NACO and SACO records.

About Library of Congress Authorities

Search and browse approximately:

   * 265,000 subject authority records
   * 5.3 million name authority records (ca. 3.8 million personal, 900,000 corporate, 120,000 meeting, and 90,000 geographic names)
   * 350,000 series and uniform title authority records
   * 340,000 name/title authority records

source: http://authorities.loc.gov/help/contents.htm

Updates

The Library of Congress updates and adds new records to their Authority File constantly. They provide updates to both their NACO and SACO records on a weekly basis to vendors.

Backstage Library Works incorporates these weekly files every Wednesday.