PAID 111 Section 12 - Peterson (Fall 2025)

Call numbers? What are they?

Call numbers are assigned to each book in the library. They are used in order to:

• Help us find materials
• Group books by subject or topic

Who came up with this?

• J.C.M. Hanson, Luther College class of 1882, was head of the Catalog Division at the Library of Congress in 1897. Working with Charles Martel, Chief Classifier, the two developed the Library of Congress Classification System and the first volumes were published in 1901-1902. This is the most commonly used call number system in college and university libraries in the United States.

Classes A - L are on the First floor of Preus.

Classes M - Z are on the Third floor of Preus.

Infographic created by McMaster University Library.