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Finding Books on the Shelf: What is the LC System?

Most academic libraries use the Library of Congress Classification System to organize their materials. This guide will show you how to use that system to find materials in the library.

What is a call number?

Every item that the library owns is given a unique call number according to the Library of Congress system.  This number is like an address for the book, telling you exactly where to find it inside the library. 

Cartoon image of a paper folding map with a large location pin sticking out of it.

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Library of Congress (LC) Classification

Libraries use classification systems to organize the books on their shelves. These systems are composed of alphanumeric call numbers (meaning letters and/or numbers) to arrange the books so that books on the same topics are shelved together. This arrangement results in what we like to call

"Serendipitous Browsing."

Serendipitous browsing means that when you find a useful book in the catalog, you can go to the shelf where it is located and find even more useful materials shelved in the same area. Sometimes sitting right next to it! The Thurgood Marshall Library, like most academic libraries, uses the Library of Congress Classification System, which is made up of letters and numbers. The LC system covers 21 different subjects, each one represented by the first letter in the call number.  Within each subject, there are also subcategories.  For example:  Q - Science,  QA - Mathematics, Computer Science, QB - Astronomy, and so forth.

Want to Know More? ...

This link will take you to an exhaustive list of Library of Congress Classifications and Sub-classifications.

LC Subject List

A - General Works

B - Philosophy, Psychology, Religion

C - Auxiliary Sciences of History

D - World History (Europe, Asia, Africa, Australia, Ect.

E - History of the Americas

F - History of the Americas

G - Geography, Anthropology, Recreation

H - Social Sciences

J - Political Science

K - Law

L - Education

M - Music

N - Fine Arts

P - Language and Literature

Q - Science

R - Medicine

S - Agriculture

T - Technology

U - Military Science

V - Naval Science

Z - Bibliography, Library Science, Information Resources