Quirks and oddities of Library of Congress Classification 

Sep 11, 2018 · Megan O'Donnell

The University Library, like most academic libraries in the United States, uses Library of Congress Classification (LCC) to organize its books by topic area. The system has twenty-one basic classes, each represented by a letter of the alphabet, and numerous subclasses, represented by a second, and sometimes third letter. For example, Education is Class L and books on Textbooks are found under subclass LT. The main classes of LCC haven’t changed since their inception at the end of the 19th century, and new topics and areas of study had to be squeezed into a framework first established 130 years ago. While LCC does undergo updates they happen irregularly and slowly, and many “artifacts” of its origins are still evident in the current system. 

Computers and computer science are a classic example of LCC squeezing: they were given a tiny range of just two numbers (QA75 and QA76) and filed under Mathematics; right between slide rules and “miscellaneous geometrical instruments”. For this reason, call numbers in computer science use a second set of letters and numbers to further organize their subclass. For comparison books on biological viruses are classed in the range of QR394 – QR502 while books on computer viruses are all found under QA76.76.C68. No doubt the small two-number slice of the QAs seemed adequate for computers back when it was first established, but it’s become a large and crowded section for such a small “slice” of the Mathematics section. 

Another quirk of LCC is that sometimes rather obscure topics are elevated and given their own classification. Some of favorites of Iowa State University librarians include: 

BF727.P5 Psychology of pharmacists

G154.5 Biographies of travel agents. The popular book “Eat, Pray, Love” by Elizabeth Gilbert is classed in this section. 

GV1808 Vocational guidance for circus clowns

HD9438.E32 Economics of the edible caterpillar industry

QL785.3 ESP in animals

PJ7632 .F55 Arabic poetry and humor on flatulence* 

SK336 Varmint hunting

TT873.2 Banana craft

*Author’s note: Yes, this is real. Only two books have been given this unique classification and sadly the ISU Library doesn’t own them.