I have never really had a solid grip on what is or is not YA, But some time in the latter half of the 80s, probably after pulling the, "I don't want to be entertained! I'm BORED!" thing once too often, I was marched into a book store and ordered to buy something. The assistant produced 2 paperbacks. One had cover art showing jeeps and helicopters and burning buildings, and whatever it was called, it didn't appeal. The other one had an awe inspiring picture of an aircraft flying over a rocky monochrome desert, and looked so delightfully desolate, I bought it first and read the title later.
For those who
don't have an encyclopaedic knowledge of cover art, it was
Cloud Warrior, the first volume of Patrick Tilley's
Amtrak Wars series. And I saved up to buy all the other books, including the separate volume glossary. (Yes, you had a special dictionary to help keep track of everything.) That series was the story that let me know that there was a reason to read novels that went beyond writing an essay to prove you've read it. (I'm still sore about the poor grade I got for my analysis of the character and motivations of Atticus in To Kill A Mocking Bird.)
Later, I read a book belonging to my mother called
Emergence, by, if I remember rightly, David R Palmer. That was a great book about a 12 year old girl and her faithful pet macaw who survive the apocalypse, only to discover that the girl is not a Homo Sapiens after all, but a member of a new species, the next evolution of man. She sets off alone, apart from the bird, to find the rest of her race and ends up crossing the US, going into orbit, and almost killing herself several times along the way.
It was full of developing self confidence, solving problems, first love, being taken seriously by real live adults, and all those other classic YA coming of age themes. I read it several times in my teens and early 20s.
Oh, and let's not forget
A Hat Full Of Sky BTW. Before I went blind, I really did buy books and records just because I liked the cover art. And I was rarely disappointed. Just goes to show, you
can judge a book by its cover. But only if you're awesome.