A very interesting post by science fiction writer Charles Stross (you can read his account of his background here, and here‘s the requisite Wikipedia article) about why the length of a typical novel has doubled since the ’60s. Here’s the heart of the explanation he got from one of his editors:
Until the early 1990s, mass market SF/F paperbacks in the US were primarily sold via grocery store racks, supplied by local distributors (400+ of them). The standard wire rack held books face-out, either against a wall or on a rotating stand. And that’s where the short form factor novel became established. Thinner books meant you could shove more of them into a rack that was, say, three inches deep. Go over half an inch thick, and you could no longer fit six paperbacks in a 3″ rack. And there was only so much rack space to go around.
During the inflationary 1970s and early 1980s, prices of just about everything soared. The publishers needed to increase their cover prices to compensate. But the grocery wholesalers who sold the books insisted “the product’s gotta weigh more if you want to charge more”. They weren’t in the book business, after all, so just as buffalo tomatoes got bigger, so did paperbacks. (Even though this meant there was less room to go round in the wire racks.) You can only get so much milage by using thicker paper and a bigger typeface; so they began looking for longer novels.
(Via MetaFilter; there’s much more detail, and discussion of why mystery novels haven’t similarly ballooned, at Charlie’s post.) How I hate that kind of economic pressure that has nothing to do with the quality of the work! And how fondly I remember those wire racks!