Not to split hairs, but American Graffiti came out over 35 years ago (1973). Yes, time does move that quickly.
I was going to respond by saying that the American Graffiti type atmosphere continued to exist along Van Nuys Boulevard up until the mid 1980s, at least the middle class apple pie America part of it. I think that might be stretching it a bit. It probably did last up until about 1980, but like you say, that is splitting hairs.