Free Exchange tries to understand why jobs have been slow to come back. Arnold Kling adds:
My thesis is that unemployment is more persistent when the layoffs
come from structural change rather than from excess inventories. With
excess inventories, once the excess has been absorbed you can go back
to work at your exact same job. On the other hand, when firms and
industries permanently shrink, you have to find a new job, and possibly
even an entirely new occupation. It is rare for people to have the
capacity to do that, and it takes quite a bit of time when they do.