Q&A: Can you explain what the letters in call numbers mean?

Question:

It's unclear to me what the letters at the beginning of call numbers mean. Can you explain what they represent and how the system works?

Answer: 

Most of the books and journals here in Green Library are classified using the the Library of Congress Classification (LCC) scheme. As the Library of Congress site explains here, the system was "first developed in the late nineteenth and early twentieth centuries to organize and arrange the book collections of the Library of Congress." This system is used at other libraries as well, especially at large academic libraries in the United States.

The system assigns a single letter of the alphabet to the 21 classes into which it divides all knowledge. Most of these single-letter classes are then divided into more specific subclasses, represented by two- or three-letter combinations. For example, class D, World History, has subclasses DA, Great Britain; DAW, Central Europe; DB, Austria - Liechtenstein - Hungary - Czechoslovakia; and so on up through DX, Romanies. You can view the 21 classes here; click on them to see their respective subclasses. You can click on the subclasses as well to see their breakdown into even more specific topics with assigned numbers (e.g., D, World History; DA, Great Britain; DA350-360, Elizabeth I, 1558-1603. Elizabethan age).

Don't forget to take a look at the Green Library Mobile Stacks Guide or at the printed Stacks Guides (available at the Information Center desk) to see where to go in the library for the call number you're looking for.