I’m not sure people on my side of the Atlantic fully appreciate quite how much better off the average American is than the average European. A car-wash manager in Alabama can now earn $125,000, about 50 per cent more than the head of cyber security at the UK Treasury even after accounting for different living costs. And this isn’t just another reflection of British stagnation — from the middle of the income distribution upwards, US households have streaked ahead of every country in the developed world over the past decade.

Such a sustained boom in spending power might, you would imagine, be accompanied by improvements in other indicators of prosperity. Longer and healthier lives, for example. But the two trends are moving in opposite directions.

That the US has a poor record on life expectancy is nothing new. For the best part of a decade, American lives have grown progressively shorter relative to peer countries. But beneath the surface, several striking details demand our attention and an urgent effort to reverse the trend.

American life expectancy compares extremely unfavourably with the UK. The English seaside town of Blackpool has been synonymous with deep-rooted social decline for much of the past decade. It has England’s lowest life expectancy, highest rates of relationship breakdown and some of the highest rates of antidepressant prescribing. But as of 2019, that health-adjusted life expectancy of 65 (the number of years someone can be expected to live without a disability) was the same as the average for the entire US.

This means that the average American has the same chance of a long and healthy life as someone born in the most deprived town in England. If you then explore how life expectancy varies across the income distribution in both countries, the results are not pretty. This is especially alarming when you consider that the UK is far from top of the class when it comes to life expectancy in Europe.

While Americans and Britons living in the richest neighbourhoods of their respective countries have similar, high life expectancies, at the bottom end it’s a different story. People born in the very poorest pockets of Blackpool are expected to live fully five years more than the poorest in the US.

This would be damning enough, but we’ve not yet accounted for the fact that the richest Americans are so much richer than their British counterparts. Once we do, Britain pulls clear at every income level. Someone with a net household income of about £65,000 or $100,000 will live to an average age of 85 in England, but only 80 in the US.

What is causing these gaps? Shockingly, America’s mortality problem is driven primarily by deaths among the young.

One statistic in particular stood out: one in 25 American five-year-olds today will not make it to their 40th birthday. No parent should ever have to bury their child, but in the US one set of parents from every kindergarten class most likely will.

And this is a very American problem. These young deaths are caused overwhelmingly by external causes — overdoses, gun violence, dangerous driving and such — which are deeply embedded social problems involving groups with opposing interests. Far trickier to tackle than most health issues where everyone is pulling in one direction.

Almost every country in the world took a mortality hit during the pandemic. Developed nations for the most part are bouncing back, but the US is not. If Covid-19 had never happened, life expectancy in other developed countries would have remained flat or increased, but the US would still have lost a year due to the surge in violent deaths. By my calculations, Americans lost 9.4 million years of life to external causes in 2021 alone, more than the 9.1mn lost to Covid over the course of the entire pandemic. And these deaths continue to rise.

The past three years have stretched social ties and tested safety nets everywhere and the US has been found wanting. But the underlying factors reveal a longer-term story of a hidden cost in life expectancy across the income groups. And the highest price is being paid in avoidable deaths among the young, the poor and the vulnerable.

john.burn-murdoch@ft.com, @jburnmurdoch