The recession may have magnified a trend that began nearly four decades ago - wage stagnation, or worse. Michael Luo at The New York Times writes,For Many, a New Job Means Lower Wages, Studies Find:

With the country focused on job growth and unemployment continuing to hover above 9 percent, there has been comparatively little attention paid to the quality of the jobs being created in this still-struggling economy and what that might say about the opportunities that will be available to workers when the tumult of the Great Recession finally settles. ...

For years, long before the recession began, job growth had become increasingly polarized in this country, with high-paid occupations that demand significant amounts of education and training growing rapidly, alongside low-wage, entry-level, service-type jobs that do not require much schooling or special skills, according to David Autor, a labor economist at the Massachusetts Institute of Technology.

The growth of these low-wage jobs began in the 1980s, accelerated in the 1990s and began to really take off in the 2000s. Losing out in the shuffle, according to Dr. Autor, are jobs that he describes as “middle-skill, middle-wage” — entry-level white-collar positions, like office and administrative support work, as well as certain blue-collar jobs, like assembly line workers and machine operators.

But now there's an additional element at work. A recent study by the National Employment Law Project points out that "net job growth in 2010 has not been distributed evenly across the economy. Growth has been concentrated in mid-wage and lower-wage industries. By contrast, higher-wage industries showed weak growth and even net losses."

The study concluded that:

• Net job losses in 2008-2009 were widely distributed. There were significant losses in higher-wage industries. But net job gains this year are disproportionately found in median industries below $15 an hour.

• At the top of the list in 2010 were three occupations - retail sales persons, cashiers, and food preparation workers - with median wages below $10 an hour.

Many people who had been in the higher-wage industries but were laid off, particularly if they were in their 50s or older, have been forced to find work in those lower-wage occupations. Not only does this make matters tougher for them, it squeezes out younger workers who typically start out in the lower-wage jobs, often while they are attending college or saving up money to do so. If this trend continues, it will exacerbate the destruction of the middle-class, both for those who managed to get there after years of work and those who seek to get there.

As noted by the Financial Times in its look at the vanishing middle class:

The slow economic strangulation of the Freemans and millions of other middle-class Americans started long before the Great Recession, which merely exacerbated the “personal recession” that ordinary Americans had been suffering for years. Dubbed “median wage stagnation” by economists, the annual incomes of the bottom 90 per cent of US families have been essentially flat since 1973 – having risen by only 10 per cent in real terms over the past 37 years. That means most Americans have been treading water for more than a generation. Over the same period the incomes of the top 1 per cent have tripled. In 1973, chief executives were on average paid 26 times the median income. Now the ­multiple is above 300.

It shows how far we've come that, given today's economy, treading water sounds like an improvement.