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Understanding Call Numbers: Library of Congress Call Numbers

This guide is to help understand how call numbers help are used to organize materials.

Library of Congress Classification (LC)

LC call numbers begin with letters. 
In the online catalog, typical LC call numbers look like:

 HB3505 .E44 1992

On book spines, or labels on other materials, LC call numbers are arranged vertically and would typically look like:





Subject Areas

Library of

Congress Classification


 A– General Works

  AE– Encyclopedias


  AY– Yearbooks, Almanacs, Directories



  BD - Philosophy



  BL-BX—Religion, Mythology

C– History-Auxiliary Sciences

  CB– Civilization




  D– World History

  DA—Great Britain

  DB– Eastern Europe

  DE-Mediterranean Region


  DR—Balkan Peninsula

  DS—Asia & Middle East


E-F– America

  E 1-143 - America

  E 151-857—US (General)

  F 1-957—US (Local)

  F 1001-1140 - Canada

  F 1201– Central & South America


  GB– Physical Geography



H-Social Science


   HE—Transportation & Communication



   HQ—Family, Marriage, Women

    HT– Cities, Communities, Race

    HV– Social Service, Welfare, Criminology

Library of Congress Call Numbers

Understanding the Parts of Library of Congress Call Numbers

Library of Congress (LC) call numbers can be a challenge to read when you first start using LC classification. This LibGuide was created to help library users uncover the mysteries of call number reading. Let's start by looking at a book in our collection:  Elephants in the Volkswagen : facing the tough questions about our overcrowded country by Lindsey Grant.  This books call number is:

HB3505 .E44 1992

Let's break this call number down and learn how to read it.

Call numbers can begin with one, two, or three letters.

  • The first letter of a call number represents one of the 21 major divisions (bold text in the boxes to the sides) of the LC System. In the example, the subject "H" is Social Science. The added "B" breaks it down to Economics subdivision.
  • Most of the subject area divisions have one or two letters. However, there are some that have only one (E-America) or can have up to three letters (K-Law).
  • For most of the subject areas, the single letter represents books of a general nature for that subject area (i.e. Q - General Science or D - General World History).           

Numbers after letters.

  • The first set of numbers in a call number help to define a book's subject and are read as a whole number. This number can be one digit, several digits, and even have a decimal.  In the example, "3505" tells us this book is about general United States demography or information about the population.  
  • Books with call numbers that start with HB3501-3697 are about the demographics of different regions or countries.

Cutter Number

The cutter number is a coded representation of the author or organization's name or the title of the work (also known as the "Main Entry" in library-lingo).

  • Charles Ammi Cutter first developed cutter numbers using a two-number table.
  • A three-number table was developed in 1969.

In our above example, HB3505 .E44 1992, the .E44  represents the first three letters of the book title Elephants in the Volkswagen : facing the tough questions about our overcrowded country by Lindsey Grant. Some books have two Cutters, usually a further breakdown of the subject matter.

For example, QA 76.76 H94 M88 is a book located in the Mathematics section of the Q's.

  • QA 76 is about Computer Science.
  • The ".76" indicates Special Topics in Automation.
  • "H94" tells us that this is a book about HTML.
  • "M88" represents the last name of the first author listed's last name, Musciano.
  •  The book is HTML: The Definitive Guide

Dates and Volume Numbers

The last number in the call number is the copyright date, the year the book was published.  This can help you quickly find a book if you need one that is more recent.  On some books you may see a volume number, with "volume" being abbreivated "Vol." or even just "V."


This covers the basics of a LC Call Number.  You can find some other numbers on labels at times, but the majority of books follow this pattern.

Just be sure to ask at any of the desks for assistance if you have questions.

Reading the LC Call Number

To read a LC call number you simply go down the label, reading each line as you go.

Let's break it down using our example above:  





You would first look for the "HB" section. All the books whose call numbers start  with HB will be together on the shelf.

You then look for the "3505". Remember this is a whole number, three thousand five hundred and five. Some books may have a decimal in this number, breaking the topic down more. All books with HB 3505 will be together on the shelf, with HB 3505 coming before any that may have a decimal after the 3505.

You then move to the next line, ".E44". Any number after the "." here is read as a decimal. You would find the books that have HB 3505 .E and look for .E44. One way to read it is E .44.  This decimal is important to remember, ".E6432" would come BEFORE ".E705" which would be BEFORE ".E9".

The last line is the date the book was published, 1992.  There can be books that are re-printed so they can have different dates here.  So 1990 would come before 1992.

Location Prefixes

Some call numbers are preceded by a location prefix indicating that the item is shelved in a specific location and may have loan restrictions. For example:

REF - Reference item located on the Reference shelves on the 1st floor, East Wing. These books do not check out.

BANDY and ROBERTS - Reference items with BANDY prefix have been donated by the Bandy Heritage Center and are located in the Bandy Heritage Center collection while the ones with ROBERTS are from the personal collection of Dr. Derrell C. Roberts, former president of the college for whom the library is named. The ROBERTS collection are housed in the library archive. These two collections do not check out.

The books that do not have a location prefix should all check out.

Subject Areas - continued

Library of Congress 

Classification System

J-Political Science

    JC—Political Theory

    JF– Constitutional History

    JK– United States

    JN– Europe’

    JQ- Asia, Africa, Australia, Oceania

    JS—Local Government

    JX—International Relations & Law



    LA- History of Education

    LB- Theory & Practice

    LC-Special Aspects

    LD- U.S. Institutions


    ML - Literature of Music

    MT - Musical Instruction

N- Fine Arts

    NA– Architecture

    ND- Painting

     NE- Print Media

P-Language and Literature

     PA- Classical Languages

     PC- Romance Languages

     PE- English Language

     PN- General & Comparative Lit.

     PR- English Literature

     PS- American Literature

     PZ- Fiction: Juvenile Literature


     QA- Math & Computer Science

     QC- Physics

     QD- Chemistry

     QH- Natural History, Biology

     QM- Human Anatomy

     QP- Physiology



     RA- Public Health

     RB- Pathology

     RC- Internal Medicine

     RD- Surgery

     RJ- Pediatrics

     RT- Nursing


T- Technology

     TA- Civil Engineering

     TD- Environmental Technology

     TH- Building Construction

     TK- Electronics

     TP- Biotechnology

U-Military Science

V-Naval Science

Z-Bibliography & Library Science