OVER the last decade, the United States has become a less violent country in every way save one. As Americans commit fewer and fewer crimes against other people’s lives and property, they have become more likely to inflict fatal violence on themselves.

In the 1990s, the suicide rate dipped with the crime rate. But since 2000, it has risen, and jumped particularly sharply among the middle-aged. The suicide rate for Americans 35 to 54 increased nearly 30 percent between 1999 and 2010; for men in their 50s, it rose nearly 50 percent. More Americans now die of suicide than in car accidents, and gun suicides are almost twice as common as gun homicides.

This trend is striking without necessarily being surprising. As the University of Virginia sociologist Brad Wilcox pointed out recently, there’s a strong link between suicide and weakened social ties: people — and especially men — become more likely to kill themselves “when they get disconnected from society’s core institutions (e.g., marriage, religion) or when their economic prospects take a dive (e.g., unemployment).” That’s exactly what we’ve seen happen lately among the middle-aged male population, whose suicide rates have climbed the fastest: a retreat from family obligations, from civic and religious participation, and from full-time paying work.

The hard question facing 21st-century America is whether this retreat from community can reverse itself, or whether an aging society dealing with structural unemployment and declining birth and marriage rates is simply destined to leave more people disconnected, anxious and alone.