Library of Congress Call Number Overview: Introduction

Learn more about the Library of Congress classification system, how to interpret call numbers, and call number locations.

Introduction to Call Numbers

The image shows a blonde woman with dialog bubbles in red (yellow font) "Looking for a book?" and a green bubble (yellow font) "Find the call # in the catalog, but". Click on the video on your left (courtesy of Yavapai College Library).  Learn more about the call number system we use at RIT Libraries. We use the Library of Congress (LC) system (used at many academic libraries) to classify our materials which include books, bound journals, microfilm, and videos.

Find the correct shelf range for your book by using the floor maps Note that the same call number will apply to diverse materials located in different areas. Example: Deaf Studies tend to be in the HV2300-2600 call number area. If you are looking for Deaf Studies books, bound journals, microfilm, reserve materials, and deaf media, you will look for this call number, HV2300-2600 across all materials and locations related to this topic.

On the end of each row in the library, you will find the call number range posted. You probably will not see your exact call number listed, so you need to locate where yours falls within that range. Using our example of NA5205 .H69 2003, start by looking for the section containing call numbers beginning with an "N." Once you have found the “N” section, look for a range that has "NA" in the row. While it does not explicitly state that “NA” is contained here, we know that NA5205 .H69 2003 is in this row because “NA” comes after “N” and before “NB.” (Material from Seminole State College of Florida).

Interpreting Call Numbers

Book spine with call number NA5205 .H69 2003Image from Seminole State College of Florida

 Each book has a label on its spine with the call number. Each group of numbers and/or letters is code for a particular a subject area, subtopic, author information, and publication information. For example, the decoded call number for the book NA5205 .H69 2003 is:

NA = Subject Area (Architecture)

5205 = Subject Area Subtopic (Religious Architecture)

.H69 = Author's Last Name (Howe)

2003 = Publication Date (2003)

Call numbers not only allow you to find a specific book, but help you browse subject areas. For example, if you find one book on Claude Monet’s paintings (ND55 .M7 M6 1999), you can look to the left, right, above, and below that book for others on the same or related topics. Some broad topics, like pollution, are in multiple subject areas depending on the information's focus (law, business, social issues, etc.), so it is best to find a few different call numbers and browse those sections.

Reading the Shelves

The image shows two bookshelves and how to read them with green arrows going from left to right, and down to the next shelf. After you are on the correct floor and have located the appropriate call number range, go down the row and look at the individual shelves and books. It is helpful to think of finding a book with a call number as a matching game - each call number corresponds with usually just one book on the shelf (the book's address).

Scan the books from left to right, top to bottom, one 3-ft section of shelving at a time. With NA5205 .H69 2003 as our call number, you first find books that match the "N" category, followed by those labeled with "NA" in the call number.

Once in the correct section, find books with "5205" after the “NA.” Remember that if you have found the "NA5000" section, you must keep going to the right.

If you have reached "NA6000," though, you have gone too far and must look back to the left. When you have found “NA5205,” look for the book that has the remaining call numbers ".H69," and then finally the year of publication (note: some older books will not have a year of publication).

(Material from Seminole State College of Florida).

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