Lesson 2: The Library of Congress Classification System


Academic libraries in many parts of the world use a different system, the Library of Congress (or LOC) Classification System. This organizational scheme is much different from the Dewey system in both the structure of the classifications, the format of the classification code, and therefore in the way it physically organizes the resource materials in the library.

The LOC system is organized into 21 alphabetic class codes. The contents of each of these classes is fully described in individual PDF files accessible on the Web at the Library of Congress Web site at the page at <www.loc.gov/catdir/cpso/lcco/lcco.html>. The main alphabetic class codes may also be broken down into subsidiary multiple-letter subclasses. Within each class and/or subclass are further divisions into more granular detail for producing a finite classification number for each item. Let’s explore several of the main classes and subclass areas that will be of interest to genealogists.

LOC Class D represents History (General) and History of Europe. Subclass DA represents Great Britain. Reference materials about Wales are classified in the range of DA700-745, with DA740-745 representing Local History and Description. Subclass DAW and DAW1001-1051 represent History of Central Europe, with DAW1001-1028 containing General history materials and DAW1031-1051 focusing on History. You’ll note that there are numerical gaps to allow for additional growth.

Classes E and F are interesting in that they both relate to History: America. Class E focuses on American History. Class F, on the other hand, concentrates on the history of North and South America. It contains further, more finite divisions relating to the American states and territories, British America, Dutch America French America, and finally Latin/Spanish America.

Class C contains the genealogical material most frequently accessed by genealogists researching family history and related subjects. Subclass CR and its subdivisions contain materials concerning Heraldry. Subclass CS (CS1-3090) represents Genealogy with the following divisions:

  • CS23-35 Genealogical lists covering more than one country or continent
  • CS38-39 Family history covering more than one country
  • CS42-2209 By region and country
  • CS2300-3090 Personal and family names

Class A consists of General Works of many types. Subclass AE, for example, contains Encyclopedias; AN contains newspapers; and AY consists of Yearbooks, Almanacs, and Directories. Class P is the area containing Language and Literature materials, while Class Z would be helpful in providing references on paleography (old handwriting).

As you can see from these examples, resources in each of these classes can provide essential resources and useful information for your genealogical research.