But there is evidence that in the last few months that trend has started to reverse. The proportion of the adult population in the labor force and the proportion of the population with a job are both up half a percentage point since September. For the first time in years it’s fair to say that these changes are decisively pointed in the right direction.

Just last summer, as the United States expansion entered its seventh year with booming job growth, there was reason to doubt that an improving job market would ever start to pull people in who had become detached from the labor force. After all, if seven years of job growth wasn’t enough to make more people enter the work force, what would be?

We still don’t know for sure how much more room there is to grow. Presumably most people who dropped out of the labor force around retirement age are out of the work force for good, no matter how many job opportunities present themselves. But the data in 2016 will help us find out how much room for expansion there really is in labor force participation.

There is some interplay between the growth in the number of workers and the most disappointing signal in the February jobs numbers, which was a step down in average hourly earnings. Over the last year, this number has risen 2.2 percent, which amounts to a modest rise in pay for American workers thanks to very low inflation. But it hardly suggests the kind of booming economy indicated by the low unemployment rate.