Employers and economists point to several explanations. Extending jobless benefits to 99 weeks gives the unemployed less incentive to search out new work. Millions of homeowners are unable to move for a job because the real-estate collapse leaves them owing more on their homes than they are worth.

The job market itself also has changed. During the crisis, companies slashed millions of middle-skill, middle-wage jobs. That has created a glut of people who can’t qualify for highly skilled jobs but have a hard time adjusting to low-pay, unskilled work like the food servers that Pilot Flying J seeks for its truck stops…

Some economists fear the U.S. could end up with a permanent caste of long-term unemployed, like those that weigh on government budgets in some European countries. “It is a very worrisome development,” says Steven Davis, an economist at the University of Chicago’s Booth School of Business. “It leads over a long period of time to social alienation as well as economic hardship.”