Why Are Books the Length They Are?

There's an interesting post on author Charlie Stross's blog.

From the piece...

Let's take SF and fantasy novels published in the USA as a case in point. Prior to the early 1920s the genre didn't really exist in its current form. From roughly 1923 and Hugo Gernsback's publication of Amazing Stories magazine, the pulps reigned supreme: monthly newsstand magazines publishing short stories and serializing novels. Newsstand magazine readers are fickle. Serial novels need to be short enough not to dominate a magazine completely, lest a reader who doesn't like this particular novel stops finding other reasons to buy the mag; and they need to be of finite length. It shouldn't be any surprise to discover that SF novels from the period 1923 to roughly 1952, when the newsstand fiction magazine industry more or less disintegrated (leaving only a tiny handful of survivors) are typically very short — 45,000 to 60,000 words.

The death of the pulps didn't take the SF novel with them; far from it. In fact, book-format novels were already being published (notably Asimov's Foundation series dates to this time — originally serialized in magazine form, they then saw success as individual books), and the mass market novel took over as the main outlet. The length of novels then began to creep up, and continued to creep up steadily through the 1980s.

Many earlier novels are still deceptively short by modern standards. A typical SF novel of the 1960s was 70,000 words long. By the 1980s, 80,000 words was the norm; by the 1990s it had bloated to 100-120,000 words. Why?

One account I've heard (from an editor who was active throughout this period) is that it was the distributors. The mass market for paperbacks prior to 1991 was dominated by wholesalers who supplied retail stores — not bookshops, but local supermarkets with wire-mesh book racks.