Millions of Americans aren’t working. Why?

Call it the million-worker mystery.

A large chunk of American adults are no longer in the labor force. That has left economists divided over how many of them are voluntarily not working-or even looking for work-because they wanted to retire, go to school or take care of family members, versus how many have been forced out because they couldn’t find a job.

Read more by Allison Linn at CNBC.com