© MSN Money

So much for full-time work

One main problem is that since the recession ended, the economy has been creating low-quality, part-time, no-benefit positions. You can see this in the way the percentage of Americans with a full-time job has fallen back to early 1980s levels. This, in turn, is pressuring take-home pay.

There are a few additional considerations. Americans are increasingly fighting for scarce jobs, given that millions of women have entered the workforce and swelled the available pool of labor in the past 30-plus years. The female labor participation rate is up from the high 40% range in the late 1970s to nearly 60% now, though the male participation rate is down from 80% to just 71% now. As a result, the number of people working part-time because they can't find full-time work is at 8.1 million -- up from a low of 3 million in 2000.

And the jobs that are out there aren't paying as well as the positions lost during the recession used to. The number of goods-producing jobs has decreased, while most new jobs have been in service-oriented fields that often come with lower pay. For example, construction is down about 25% from its pre-recession employment level, while bar and restaurant jobs are up nearly 10%.

Now let's look at another building block of the middle class: homeownership.