The May job numbers raise a depressing possibility: that this is as good as it will get for the United States labor market.

At first glance, the new numbers seem like a bit of a mystery. The unemployment rate fell to a 16-year low, yet job creation slowed and the number of people who are neither working nor looking for work rose. But the data aren’t really inconsistent. Rather, they point to a job market that is pretty close to full employment — where workers who want a job can find one fairly easily, but low unemployment isn’t pulling workers into the labor force en masse.

The big headline is a drop in the unemployment rate to 4.3 percent. That’s lower than it ever fell during the mid-2000s expansion, and you now have to go back to 2001 to find a moment as good. But the details of why the rate fell in May are terrible; the unemployment rate dropped for all the wrong reasons.

Instead of a decrease because more people are employed, the number of people who reported themselves as having a job actually dropped by 233,000. Meanwhile, the number of people not in the labor force at all — neither working nor actively looking for work — soared by 608,000.