National Union Catalog

American library catalog

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Last updated

July 1, 2026

Quick Summary

The National Union Catalog (NUC) is a library catalog that combines the contents of multiple libraries into a single series, typically organized alphabetically by author. This comprehensive catalog serves as a vital resource for researchers and librarians, offering a centralized index to a vast collection of materials held across various institutions.1

The Library of Congress, a prominent national library, plays a significant role in this endeavor. It makes its catalog available to thousands of subscribing American libraries and institutions, influencing librarianship through its classification systems and cataloging practices. The Library of Congress produced the extensive National Union Catalog: Pre-1956 Imprints and continues to issue the National Union Catalog on microfiche, acting as a hub for information on worldwide acquisitions and distributing cataloging data.2

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Library of Congress
…printed product was the 754-volume National Union Catalog: Pre-1956 Imprints. In 1983 the library began producing most of the National Union Catalog on microfiche (sheets of microfilm containing rows of microimages of pages of printed matter). It serves as a centralized bureau for information on the acquisition of materials worldwide…
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…printed product was the 754-volume National Union Catalog: Pre-1956 Imprints. In 1983 the library began producing most of the National Union Catalog on microfiche (sheets of microfilm containing rows of microimages of pages of printed matter). It serves as a centralized bureau for information on the acquisition of materials worldwide…
Read More