A 1960’s-early 70’s color (I think) children’s picture book about a girl who is forced to share her bedroom with a sibling. She copes by drawing a line down the middle of the room to stake out her territory.
Stump the Bookseller
New format, same book stumper solving.
I figured it out myself, when the actual title popped into my head as I submitted this post! It was in the recesses of my brain all these years. I just found it online: This Room Is Mine, by Betty Ren Wright. Crazy! There were apparently two different formats (one gold cover, small with a spiral-notebook type of binding), and the larger picture book size of one I had, which had a pink version of the same cover art (a girl looking out of her curtained bedroom window with a horse behind her, framed by the bricks of the exterior of her home). I need to find the larger, pink one, because that’s the one I had.
The one by that title, by Betty Ren Wright?
This sounds like A Room for Cathy by Catherine Woolley. Published first in 1956 and reprinted many times afterwards….most notably the 1970s Scholastic edition
Betty Ren Wright, This Room is Mine! (It also had another title–one was paperback, one hardcover, I think.)
My sister and I loved that book! The room looked so much like ours, we turned it into a play for all our relatives. 🙂
Possibly Betty Ren Wright: This Room is Mine