Put out an all-points bulletin: Millions of Americans have gone missing from the workforce.

Every month that those would-be workers are gone raises the odds that they might never come back, dimming the prospects for future economic growth.

The vanishing trend is more than a decade old, but it accelerated during the Great Recession. Throughout 2012, economists held out hope that it had stopped. But then came Friday's jobs report, and hopes were dashed.