Publisher Algonquin on Wednesday announced Algonquin Young Readers, an imprint to be launched this fall. In so doing, it is  climbing on to a very crowded bandwagon.

In the last year, new young adult imprints have been launched or announced by more than a dozen publishers, operating across all adult genres. Except erotica (so far).

Mystery publisher Poisoned Pen Press created Poisoned Pencil. Science fiction and fantasy publisher Angry Robot launched Strange Chemistry. Christian publisher Zondervan announced that it will begin publishing books for teens under its new Blink imprint. C&T Publishing, which publishes crafting books, launched an imprint for tweens, FunStitch Studio.

Ig Books announced Lizzie Skurnick Books, an imprint dedicated to reissuing classic books for young adults. Amazon Children's Publishing now includes Two Lions for middle-grade readers and Skyscape for young adults. Soho Press launched Soho Teen, and Seven Stories Press launched Triangle Square. F+W Media launched Merit with bestselling author Jacquelyn Mitchard at the helm. University of South Carolina Press now has Young Palmetto Books, emphasizing a local angle. Brooklyn's powerHouse Books has announced a YA imprint, pow!

Even fiercely independent Akashic Books -- publisher of "Go the F-- to Sleep" -- has joined in, announcing that in 2014 it will begin publishing books for young adults under a new imprint, Black Sheep.

What's the reason? Readers, or more specifically, book-buying readers. It's been obvious since midway through the Harry Potter series that books for kids could sell big -- in part because adults are reading the books as well. The success of the "Twilight" and "The Hunger Games" series proved that what might have looked like a trend is more like a habit. There are young adult book buyers are to be had.

Books for young readers come in many, sometimes overlapping categories. There are books for teens, young adults, middle-grade readers and children; there are chapter books and, for younger children, picture books and board books. Unlike the clear audience definitions of movie ratings, it can be hard to figure out exactly where a book for young readers fall. Some young adult books don't identify themselves as such on their covers.

That's because the open secret about the popularity of young adult books is that adults are reading them. The reasoning seems to be that adults are more likely to buy books they find interesting if it doesn't declare "for ages 11-13" on its front cover.

But even with adults in the mix, can there be enough readers of books for young adults to go around? With so many publishers seeking the same audience, it's hard not to imagine that a few will fail to take hold.

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