America at 250: the country seems in crisis but it’s hard to make out what that means for its longevity

So, is America on its last legs, or is it going through a middle-age crisis, or simply a reset for a long innings ahead? Like with the canine epigenetic clock, we must be careful in our analysis: this need not be a phase in which it ticks faster, as national ageing has no biological inevitability, nor would it be merely such a clock at work.