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Pic of Week: A Monumental Achievement

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National Union Catalog Pre-1956 Imprints, 5th floor, Center Room, John Adams Building. (Photo by J. Harbster, 2011)

Our Pic of the Week features one of the walls in the center room of the Science and Business Reading Room that houses the massive National Union Catalog Pre-1956 Imprints set.

 I bet many of  you are asking, “What is the National Union Catalog?”

Commonly referred to as the NUC or Mansell (Mansell is the publisher), the National Union Catalog Pre-1956 Imprints is basically a book catalog*- it contains the card catalog records of book holdings from libraries in the United States and Canada up to August 1977. The concept is similar to today’s OCLC’s Worldcat.

This 3-ton bibliographic masterpiece consists of 754 volumes (volumes 686-754 are a supplement of cards received after the project began in 1967 through Aug. 1977). The complete set has approximately 528,000 pages, contains over 11 million author entries, and cost $34 million dollars to produce!

You might also be asking why we keep the set, which takes up over 125 feet of linear space, in the reading room?  It proves its value every time we need it. For example some of the Library’s online catalog records contain mistakes, e.g. incorrect call numbers or misspelled author/title.  When we come across these discrepancies, we turn to the NUC to find the book and fix the error.

Some of our readers might not know about the NUC’s rich history, so I will be posting more about this monumental work in the coming weeks.

* There are other Union Catalogs such as the National Union Catalog of Manuscript Collections (NUMC), and National Union Catalog. Cartographic Materials.


  1. Dear Jennifer,

    With my less-experience it is hard
    to find into the library of congress.

    For this i wondering, if those monumental
    achievement also are data-based ?

    your sincerely

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