There are only seven U.S. publishers of children's literature.
No, not really. There are dozens. Hundreds. But, as a bookbuyer for an independent store, it sometimes it feels like there are just seven. Why? For several reasons.
First, (as you might expect) the big companies have bought the little companies. Little, Brown was bought by Time Warner. Time Warner was bought by Hachette. So, when I want to order a book by Little, Brown, I call Hachette.
Second, the big companies have tons of imprints. Arthur A. Levine Books (the U.S. publisher of Harry Potter) is an imprint of Scholastic. When I want to order an Arthur A. Levine book, I call Scholastic (except that HarperCollins does the distribution for Scholastic... see the next point... so actually I call HarperCollins.)
Third, a few of the really large publishers handle the ordering and distribution for publishing houses other than their own. For example, Random House handles the sales for National Geographic Books. Random House doesn't own National Geographic, they just take the phone calls, place the orders and ship the books. By contracting with Random House, National Geographic doesn't have to hire their own distribution staff.
If a customer asks if we have a book in our store, my first mental question is always: who's the publisher? And not just who is listed on the dust jacket. The copyright may say Dutton, but I know that Dutton is owned by Penguin. What I really want to know is: who do I call? You can't go by who the author is. Lots of authors have more than one publisher. For example, half of Sandra Boynton's books are published by Simon and Schuster, and the other half are published by Workman.
And even once you know who the publisher is, it's never straightforward. For Candlewick, you have to call Random House. For Scholastic, call HarperCollins. For First Second (which is an imprint of Roaring Brook) call Macmillan (which used to be called VHPS). And on and on and on. You get used to it after a while, but it's tough remembering who owns and distributes who. I've got a long spreadsheet with all this information on it and it's filled with cross-outs and additions.
Houghton Mifflin just bought Harcourt. Kingfisher moved from Houghton Mifflin to Macmillan. It never stops.
And, obviously, this situation exists outside of children's books. In a previous job, I worked with scientific and technical books and we dealt with hundreds of publishers. Still, there were about seven gigantic companies we were always calling. Interestingly, the major publishers in that field are completely different than the major publishers of children's books, so I had to learn a whole new set of imprints and distributors when I changed jobs.
So, to me, it feels like there are only seven children's publishers. Even though I know that's not true.