According to the government's broadest measure of unemployment, some 17.5 percent are either without a job entirely or underemployed. The so-called U-6 number is at the highest rate since becoming an official labor statistic in 1994.

The number dwarfs the statistic most people pay attention to—the U-3 rate—which most recently showed unemployment at 10.2 percent for October, the highest it has been since June 1983.

The difference is that what is traditionally referred to as the "unemployment rate" only measures those out of work who are still looking for jobs. Discouraged workers who have quit trying to find a job, as well as those working part-time but looking for full-time work or who are otherwise underemployed, count in the U-6 rate.

With such a large portion of Americans experiencing employment struggles, economists worry that an extended period of slow or flat growth lies ahead.

"To me there's no easy solution here," says Michael Pento, chief economist at Delta Global Advisors. "Unless you create another bubble in which the economy can create jobs, then you're not going to have growth. That's the sad truth."

Pento warns that forecasts of a double-dip ("W") or a straight up ("V") recovery both could be too optimistic given the jobs situation.

Instead, he believes the economy could flatline (or "L") for an extended period as small businesses struggle to grow and consequently rehire the workers that have been furloughed as the U-3 unemployment rate has doubled since March 2008.

As that trend has happened, the U-6 rate has expanded at an even more dramatic pace. Economists cite several reasons for the phenomenon.

For one, more workers are becoming discouraged as real estate—the focal point for the expansion in the earlier part of the decade—has collapsed and taken millions of directly related and ancillary jobs with it.