The rise and fall of genre differentiation in english-language fiction

The organization of fiction into genres is a relatively recent innovation. We cast new light on the history of this practice by studying the strength of the textual differentiation between genres, and between genre fiction collectively and the rest of the fiction market, in a collection of English-language books stretching from 1860 to 2009. To measure differentiation, we adapt distance measures that have been used to evaluate the strength of clustering. We use genre labels from two different sources: the Library of Congress headings assigned by librarians, and the genre categories implicit in book reviews published by Kirkus Reviews, covering books from 1928 to 2009. Both sources support an account that has genre differentiation rising to (roughly) the middle of the twentieth century, and declining by the end of the century.