Library of Congress (LC)

Sticker on book showing an example of an LC call number

  How to read an LC call number: 

  • Read call numbers from top to bottom.
  • Read the first line from left to right.
  • Read the second line as a whole number: 1, 2, 3, 45, 100, 1000, 2000, 2430…
  • The third line is a combination of a letter, followed by numbers. Read the numbers as a decimal. Ex:  “decimal point C 65”




Collection:  Sometimes the top line will identify a collection type. For example, the Oversize collection.  If not specified, the item belongs to the general “stacks collection”.



Classification:  Based on the subject. Items with the same subject will sit on the shelf next to each other.




Cutter:  Comes from the author’s last name. Items with the same subject are then alphabetized under the author’s last name (or by title if there is no author).

2011    Year: The publication (or copyright) date comes last.

Understanding the LC System and Shelf Order

Most of the call numbers in our library are created using the LC Classification System.  This system was created by the Library of Congress.  It is divided up into 26 subjects, one for each letter of the alphabet.  Items are arranged on the shelf from left to right alphabetically by the letters on the top line of their call number. Then they are broken down further by the numbers on the second line of the call number.  They go in numerical order, ex: 3 then 4, and 21 then 207.  The numbers after the period act like decimals, ex: 1.499, then 1.51, then 1.6.

An image that includes icons and brief descriptions of each of the Library of Congress Classification System areas. 

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