DURING the post-war heyday of our middle class, jobs at General Motors and IBM were often jobs for life.  Employers offered decent wages, health insur­ance, paid vaca­tions and good pensions.  Workers’ pay and re­sponsibilities tended to rise with seniority.

In today’s global­ized and automated economy, however, good wages and long-term employment are rare.  Workers are expendable—often they’re literally “temps”—and their benefits are shrinking.  And that’s unlikely to change.

It’s also unlikely that jobs of the future will pay more than today’s (adjusted for inflation).  In unionized industries like autos and airlines, two-tier contracts are now the norm.  This means that younger workers get paid substantially less than older ones for doing the same work.

Nor is the picture brighter in other industries.  The chart below shows the US Labor Department’s list of the ten fastest-growing occupations between now and 2020.

Top Ten Growth Occupations

WHAT THESE numbers tell us is that the middle class in 2020 will consist largely of nurses and teachers.  Never mind that these occupations depend in one way or another on public funding, which nowadays is shrinking.  The deeper question that leaps from these numbers is: Where are the mil­lions of good-paying jobs that are needed to sustain a large middle class?  The Labor Department doesn’t say.  Nor does anyone else.