Why do books publish on Tuesdays?

This week, on Tuesday, Ann Patchett's new novel, "Commonwealth," will be published.

So will Ian McEwan's "Nutshell," and Marisa Silver's "Little Nothing."

"The Lesser Bohemians," a novel by Eimear McBride, comes out on Sept. 20, and Ruth Franklin's biography of Shirley Jackson comes out Sept. 27.

Tuesday, all will be published on a Tuesday. New books almost always pub on Tuesday. But why?

Of all the anonymous days of the week, Tuesday is the most anonymous. It's not the beginning of a long, dreary week, nor is it the end. It's not yet hump day, seldom payday, rarely a holiday.

Still, books have pubbed on Tuesdays for as long as I've been in this job ­— eight years already! — and for years before that. Even if they have the books in stock, booksellers are not supposed to sell books before pub date.

I have never known why. So I asked. I asked a lot of people — publishers, publicists, editors, distributors, writers for trade journals. As it turns out, nobody knows, not really. It's all guesses.

The consensus seems to be that it comes down to three things: ease of distribution, a level playing field for booksellers and a better shot at the bestseller list.

"As far as I have known, it's always been done this way for shipping," said Todd Doughty, vice president and executive director of publicity for Doubleday. "A Tuesday on-sale date allows our warehouse to ship to the West Coast with plenty of buffer time in order for the books to arrive prior to on-sale … so that all accounts receive equal treatment."

Nicholas Latimer of Alfred A. Knopf thought it had to do with The List: "Having the ability to equally distribute a large number of books across the country on the same day allows stores to begin selling big books [at the same time]. Those sales, when combined, will help place a book higher on national bestseller lists," he said. "Most stores tabulate and report their sales for any given week on Monday, and then start fresh on Tuesday."

Jim Milliot, editorial director of Publishers Weekly, thought the idea of a uniform pub date was inspired by other industries.

"They used to release them pretty much any day of the week," he said. "But they seemed to grow to like the idea of setting one day aside so accounts would know when to have the new titles on the shelves — like movie companies releasing on Friday, or video games Tuesday."

All of those answers make sense. But perhaps the best response came from Michael Reynolds, editor in chief of Europa Editions.

"Ha, ha. No bloody idea," he said. (He's allowed to talk like that; he's from Australia.) "Just like I don't know why they eat gnocchi on Thursdays in Rome.

"It probably has something to do with Nielsen, right?" (Nielsen Book Scan tracks sales info for books.)

"Or maybe it's because Tuesday takes its name from the god of battle."

Hmmm. Shipping? Bestseller list? Or Nordic god of war? In any case, for the very latest in what to read (including "Commonweath" and "Nutshell"), head out on Tuesday to your favorite bookstore. Help give Tuesday its own identity. For whatever reason.

Laurie Hertzel is the Star Tribune's senior editor for books. On Twitter: @StribBooks. On Facebook: facebook.com/startribunebooks