The U.S. job market is showing signs of a sustained recovery. But the country’s prolonged struggle with unemployment will leave scars that are likely to remain for years, if not generations.

The latest labor-market snapshot, out Friday, gave cause for continued, if tepid, optimism. U.S. employers added 200,000 jobs in December, and the unemployment rate ticked down to 8.5%, its lowest level since early 2009.

But economists gathered here for the American Economic Association’s annual convention took a longer and generally dimmer view. Even if recent progress continues, the recession already has had a lasting effect on a generation of workers. Worse, the crisis has laid bare problems in the U.S. labor market that won’t quickly recover when the economy eventually rebounds. And the longer that unemployment remains high, the greater the risk that it will create structural problems that will endure.