Library Classification Systems

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Libraries use classification systems to organize library materials so they can be easily and quickly found. These systems place items about the same subject in the same area of the library. Two systems commonly used in the United States are the Library of Congress Classification (LC) system, and the Dewey Decimal Classification (DDC) system.

  1. Library of Congress Classification System
    1. Call numbers
    2. Shelf order
    3. Collection codes
    4. Locating books
    5. Missing books
    6. Reciprocal borrowing
  2. Dewey Decimal System

1. Library of Congress Classification System

The Library of Congress Classification system is used in most college and university libraries. In the Sherratt Library, the LC system is used in all collections except the Curriculum and Juvenile Collections on the Third floor, which use the Dewey Decimal Classification System. The DDC is used in school, public, and small libraries.

In 1899, the United States Library of Congress created a classification scheme for books. It is called the Library of Congress Classification system (LC for short). In this system, all knowledge is divided into 21 broad subject areas by letters of the alphabet (I, O, W, X, and Y are not used). There is no significance for the letters of the alphabet chosen for each broad subject area. There is no need to memorize this classification system, but it is helpful to know how it works so that you can quickly find books.

Here's an outline of the major subject areas in the LC system:

A - General Works - encyclopedias M - Music
B - Philosophy, Psychology, Religion N - Fine Arts
C - History - Auxiliary Sciences P - Language and Literature
D - History (except American) Q - Science
E - General U.S. History R - Medicine
F - Local U.S. History S - Agriculture
G - Geography, Anthropology, Recreation T- Technology
H - Social Sciences U - Military
J - Political Science V - Naval Science
K - Law Z - Bibliography and Library Science
L - Education  

A second letter is then used to further subdivide the subject area.  For example, the "G" subject category is divided into these subdivisions: 

G Geography
GA Mathematical geography
GB Physical geography
GC Oceanography
GF Human ecology
GN Anthropology
GR Folklore
GT Manners and customs
GV Recreation

Each subject subdivision is then further divided into specific topics using numbers. This combination of subject areas (letters) and numbers is called the call number for that book. 

a. Call Numbers

The Sherratt Library assigns each library item a unique call number according to the Library of Congress Classification system. The call number is a unique "address" for  that item. You need this call number to find a book in the library. The call number is available from the library catalog, and is printed on the spine or cover of each book.

A call number begins with one or two letters. The call number for the book shown here is:

GV 989 .A52

b. Shelf Order

Books are placed on the shelves according to these call numbers. Books are shelved from left to right according to the LC system. Books are arranged first by the alphabetical top row, then by the number in the second row, finally by the alphabetical letter and decimal number in the third row:


Remember, when using decimal numbers, numbers will be smaller to larger, left to right! (For example, when comparing .A4010 with .A52 by position, the 4 is smaller than 5 so .A4010 comes first.)

If you understand how the LC system works in the Sherratt Library, you'll be able to walk into the Marriott Library at the University of Utah, or the Harold B. Lee Library at Brigham Young University, or the Widener Library at Harvard University and find books!

c. Collection Codes

Collection codes are identifiers added at the beginning of the call number to indicate a particular collection:

Code Collection Location
Curr Curriculum Collection Garden
IM Instructional Media Garden
Juv Juvenile Collection 3rd
Oversize Main - Oversize 3rd
Ref Reference Collection 1st
SpColl Special Collections Garden

d. Locating books

Main Collection - call numbersWhen you've found a book in the library catalog, be sure to note:

  • Call Number
  • Collection
  • Be sure it is available for checkout
  • With this information, you can go to that collection, and to the shelf where it is located.

    For example, suppose you want to find the book Roughing It, written by Mark Twain. It is in the Main Collection on the Second floor, call number

    PS 1318 .A1

    As you move through the book shelves, check the signs on the wooden ends of the  shelves. Notice that the call number falls within the range of the shelf in this picture.

    Call numbersAs you go down this aisle, look at the spine labels on the books. You see there are several books labeled PS 1318. Then look for the .A1 portion of the call number. Notice that there are other books on this shelf authored by Mark Twain.

    TIP: Once you find an item on the shelf, browse items nearby. Books are shelved according to subject, so you may find something useful.

    e. What if a book is missing?

    If the library catalog Copy Status indicates that an item is "Checked In" but you cannot find it on the shelf, follow these steps:

  • Double-check the collection and call number.
  • Look on nearby shelves to see if the item has been incorrectly shelved.
  • Look on the red return shelves near the area.
  • Ask someone at the Circulation Desk if the item is on a reshelving cart.
  • Hint: When you take an item off the shelf, don't try to put it back yourself. Instead, put it on a red shelf so that a librarian can make sure it is returned to its correct location.

    f. Reciprocal borrowing

    As a student at SUU, you can use your SUU ID to borrow books from other academic libraries in Utah. Before you go to another library, you should know there is a library catalog that lets you search any or all of the academic libraries in Utah - it's called Utah's

    2. Dewey Decimal Classification

    The Dewey Decimal Classification system is used for the Curriculum and Juvenile Collections. These book collections are used mainly by education students. This system uses numbers to group books by subject:

    Dewey Decimal Classification System

    000 - Generalities (e.g., encyclopedias)
    100 - Philosophy and Psychology
    200 - Religion
    300 - Social Sciences
    400 - Language
    500 - Natural Sciences and Mathematics
    600 - Technology (Applied Sciences and Medicine)
    700 - Arts, Entertainment, and Sports
    800 - Literature and Rhetoric
    900 - Geography and History