I wholeheartedly recommend George Packer's The Great Unwinding. Not because it gives reasons, but because it gives you a full-scale, anecdotal view of the past 60 years of American history.
As to Rockwell, I spent the better part of a year hunting this down. A copy hangs in the Los Angeles Science Fantasy Society. I printed out and mounted a full-size (24x40) version and had it mounted for a friend for his housewarming.
He thought it was science fiction.