Dewey → Library of Congress Classification

The History, Philosophy, and Newspaper Library (HPNL) and African American Studies Research Center (AASRC) are reclassifying their book collections, switching from Dewey Decimal Classification (DDC) to Library of Congress Classification (LCC).

Classification systems determine how books are arranged on the shelf, and a classification number forms the basis of each book’s call number.

Librarians created classification schemes to support shelf browsing. Shelf browsing complements other forms of information discovery, like browsing subject headings in a library catalog, and performing keyword searches in digitized book collections. Subject heading and keyword searches require what the librarian Thomas Mann called “prior specification”, by which he means patrons must know the words that name their subjects before they can formulate an effective query. Classification schemes facilitate the discovery of books on related, but perhaps unknown, topics.

Classification schemes are also able to articulate subject relationships not easily captured by subject headings alone. For example, while DuPage County and Will County are widely separated in an alphabetical listing of subjects, a classification scheme can make them adjacent, so that books about the history of DuPage County sit on the shelf near books about Will County. Classification schemes thereby collocate books on two closely related subjects.

The DDC is a more abstract classification scheme than LCC: DDC attempts to describe the entire universe of knowledge, and is essentially a system of rules for building classification numbers that, in theory, can describe any knowledge record. LCC, in contrast, is more concrete: each LCC number literally describes a book in the Library of Congress’s collection. LCC is sometimes called a “mark it and park it” classification scheme! Librarians cannot create new numbers with LCC—all possible LCC numbers are listed in the LCC schedules, and for this reason the LCC is called an enumerative classification scheme. DDC on the other hand is an example of a synthetic classification scheme.

Although DDC is the most widely used classification scheme in the world, almost all major research libraries use LCC. By switching to LCC, the HPNL will make its collections more easily usable by scholars coming from other institutions, including new faculty and graduate students. Several other departmental libraries at the University of Illinois have already switched to LCC, and many of the newest books in the Main Stacks are classified in LCC.

For more on LCC at the University of Illinois Library, see the Library’s Guide to LCC.

Watch for this exciting change coming to the HPNL and AASRC!

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