IN 2015 Anne Case and Angus Deaton, economists from Princeton University, revealed that white, middle-aged Americans with limited education were dying in greater numbers, while people of other ethnic groups and in other countries were living longer. But it is not only Americans at the tail end of the baby boom who are dying too soon. Young adults in America die at far higher rates than in other developed countries. And, as with older Americans, progress against young mortality in America over the past two decades has been slow. In 1999, the death rate for those aged between 20 and 24 was 91 per 100,000. In 2015, the latest figures show, that had barely declined to 89 per 100,000.

In 2012, when George Patton from the University of Melbourne and his colleagues reported international mortality data among young people, the annual death rate for men aged between 20 and 24 was 144 per 100,000. For women of the same age, the death rate was 48 per 100,000. The male-female gap was similarly large in many European countries, but overall death rates for the age group were about half the size. In Germany, for example, young men died at a rate of 60 per 100,000 and women at a rate of 22 per 100,000.

What is the cause of this disparity? The data suggests that suicide rates amongst young men in America were somewhat higher than in European countries, but for women they were lower than in Germany, Sweden or France. Violence and traffic fatalities, meanwhile, constituted one half of male deaths and nearly four in ten female deaths among 20 to 24-year-olds. In Britain, in the same age group, they made up one quarter of deaths for men and less than one in five for women.

The gap in deaths from violence is particularly large: a tenfold or greater difference in death rates between people in their early twenties in America and in France, for example. But young women in America are almost three times as likely to die in a fatal car accident than are women in Britain, France, Germany and Sweden (which still leaves them less than one third as likely to die in a crash than American men of the same age).

Americans of all ages are more likely to die from both traffic accidents and violence: the traffic fatality rate per person is 11 per 100,000—nearly four times the rate in Britain and a little less than three times that in Germany, for example. But rates of both violent deaths and traffic deaths peak among young American adults, widening the international disparity in mortality.

The prevalence of guns is almost certainly the main reason for the high rate of violent deaths. The explanation for the high number of traffic accidents may be more complex. In America, a dependence on cars is reinforced by a shortage of other forms of transport. But the country’s traffic death rate is almost twice the Swedish rate in terms of deaths per kilometre driven. And traffic accidents among men aged between 20 and 24 in Australia and Canada are only 55% and 63% of levels in America, respectively.

That suggests that behavioural factors play a role. And indeed, a considerable proportion of traffic fatalities in America, especially among young drivers, involve alcohol, speeding and distracted driving. Among drivers aged between 21 and 24 involved in fatal crashes, 30% have a blood alcohol content of above the impaired driving standard, compared to less than 20% in the rest of the population. A study by the US Centers for Disease Control suggested that more than two thirds of American drivers had used their mobile phone while driving in previous 30 days—a distraction that is likely to skew young.

It is to be hoped that gap between America and other countries closes. But gun reform is almost certainly off the agenda of a Republican Congress in Washington, DC. When it comes to traffic deaths, technological changes may provide more hope. Perhaps American mortality exceptionalism will decline when drunk and texting young adults are safely in the back of the self-driving car.