Nostalgia is anywhere but here.

NPR, on nostalgia

For an individual, nostalgia is a function of memory. But for a culture, nostalgia is a kind of travel. It is about somewhere else, somewhere different but vaguely recognizable, another place to look at the sunset. If we were really looking for a time when things felt easier, after all, we wouldn't love times of war and social upheaval; we'd be making shows about the dot-com boom. But we don't, because it isn't different enough yet. It has to be elsewhere; it cannot be here, because we cannot be here, not always, not every day.
What's eternal about nostalgia is the same thing that's eternal about travel: It will always happen, not because what's out there is so special that it will pull us out through the windows, but because what's in here is, at least some of the time, so difficult that it will push us out through the door.