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. (Source : CNBC )