This is a post-atomic war novel, set in *and written in* the late '50's, recounting the experiences of a small town in pre-civil rights rural Florida after the bombs hit. Well written, well thought out, good characters, including good African-American characters who are not cartoons.
If I were teaching history to HS kids, I'd want to assign this to convey both the cold war and race relations of the period (just like I'd assign "The Unpleasantness at the Bellona Club" by Dorothy Sayers to convey the effect of WW I on British society).
By putting all of this "good for you" freight on the book, I'm afraid that I'm distracting from the fact that this is one hell of an entertaining read. I first read it as a teen; I'm now in my 50's and have read it probably 20 times and it stands up.