The National Union Catalog of Manuscript Collections (NUCMC) is a free-of-charge cooperative cataloging program operated by the Library of Congress. On the basis of cataloging data supplied by eligible repositories, NUCMC catalogers create MARC (Machine R

The National Union Catalog of Manuscript Collections (NUCMC) is a free-of-charge cooperative cataloging program operated by the Library of Congress. On the basis of cataloging data supplied by eligible repositories, NUCMC catalogers create MARC (Machine Readable Cataloging) bibliographic records in the RLG (Research Libraries Group) data base, a national-level database, describe collections held by participants, and establish pertinent name and subject authority headings. Descriptions and locations of the material are then available to researchers throughout the United States and around the world.