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UMM Home > Library Home> Research Help> Research Guides> Library of Congress Classification Guide

Library of Congress Classification Guide

A Guide to the Library of Congress System

What Is a Call Number? | Three Kinds of Call Numbers | How Are LC Call Numbers Shelved? | Locating Books in Briggs Library | Outline of LC Call Numbers

In libraries the world over, call numbers serve more than one purpose:

A unique identification number

Each book (or other item) has its own unique call number which is taped to the lower outside edge of the book's spine. The call number is also written or taped inside the book, usually on the reverse side (verso) of the title page.

A miniature subject formula

Books written about the same subject have similar call numbers, which groups them together on the shelf, making it easier for you to browse the library's holdings on a specific topic.

A location code

A book's call number also appears in the catalog entry in SUMMON, the computer catalog which lists the holdings of Briggs Library. Once you have located the entry for a specific book in SUMMON, make a note of its call number and then look for the book in call number order on the library shelves (also called the "stacks").

Three Kinds of Call Numbers

Dewey Decimal Call Numbers | Library of Congress Call Numbers | SuDocs Numbers
In the United States, libraries use three different kinds of call numbers.

Dewey Decimal Call Numbers

Most school and public libraries use a system called Dewey Decimal (DDC) call numbers which begin with Arabic numerals. In Briggs Library, Dewey Decimal call numbers are used only for children's nonfiction (shelved on the third floor). In the Dewey Decimal system, fiction is usually shelved alphabetically by the author's last name, in a separate section. In Briggs Library, juvenile fiction is shelved in a separate section on the third floor, alphabetically by last name of author.

Library of Congress Call Numbers

Most academic and research libraries use an entirely different system called Library of Congress (LC) call numbers, which begin with letters of the English alphabet. For example, the book with the title A history of modern Germany : 1871 to present has the call number:

DD
220
.O67
1991

In SUMMON, the call number in the example given above is listed on a single line, with spaces between the four parts:

DD 220 .O67 1991

In the LC system, the first letter of the call number indicates the general subject area. The second letter indicates the specific sub-section within the general subject category. In the example given above, the first D in the call number indicates that the book is a work of history. The second D indicates that it is a work of German history.

In the LC system, works of fiction are assigned call numbers in the same way as nonfiction. Most works of fiction can be found in the Ps, the section for literature, located on the third and fourth floor of Briggs Library.

How Are LC Call Numbers Shelved?

Library of Congress call numbers usually have four lines or elements:

PA
112
.G53
1982

First line:

The first line can be either a single or a double letter. If a book's call number begins with a single letter which is the same as the first letter of a call number which begins with a double letter, then the book with the single letter is shelved first, or to the left, on the shelf. For example, in the section for the Ps, the correct sequence would be P PA PB PC PD to PZ, followed by Q QA QB QC QD and so on.

Second line:

The second line of an LC call number is always a whole number from 1 to 9999. If the letters on the first line of the call number are the same, the book with the smaller number on the second line is shelved to the left of the book with the larger number. (Note that in the Dewey Decimal system, the largest number is 999.)

Third line:

The third line of an LC call number is always a decimal point, followed by a letter and a number. Books are shelved alphabetically according to the letter to the right of the decimal point. For example, a book with .G on the third line of its call number would be shelved to the left of a book with .H. If two books have the same letter on the third line, then the book with the smaller decimal number is shelved to the left of the book with the larger number. For example, .G53 is shelved to the left of .G532 because .53 is a smaller decimal number than .532.

Fourth line:

The fourth line of an LC call number is always a year of publication or a volume number. An earlier edition of the same work is always shelved to the left of a later edition A lower volume number is shelved to the left of a higher volume number.

Locating Call Numbers in Briggs Library

In SUMMON, if the call number begins with or ends with REF or REF COLL, the item is shelved in the reference section on the main floor (2nd). Call numbers that begin with A-N are shelved on the first floor (basement); those whose call numbers begin with P- Q are located on the third floor. R - Z are located on the fourth floor, along with government documents.

DVD's & Videocassettes are shelved by Library of Congress call number in cabinets on the main (2nd) floor. You must look up the call number of the video you need in SUMMON in order to locate the item. Periodicals and atlases are located on the main (2nd) floor. Music scores are shelved in the Music Scores Room (#328) which is located on the third floor. Get a key from either the checkout desk or the reference desk. Educational curriculum materials are shelved in the Curriculum Collection, on the third floor. Rare books are shelved on the fourth floor along with the UMM Archives. Compact discs (CDs) are located across from the checkout desk on the main (2nd) floor. Please look up the CD number in SUMMON. For assistance in using SUMMON, please see the librarian at the reference desk.

You may wish to also review an outline of the Library of Congress classification system.