Long-term U.S. unemployment, which measures the proportion of unemployed workers who have been jobless for over six months, is at the highest rate since economists began measuring it in 1948. Of America's jobless , 45.9 percent are considered long-term unemployed, for a total of about 7 million workers. Here's what this statistic means and why it matters.

• Why Long-Term Unemployment Is Dangerous  The Atlantic's Derek Thompson explains, "long-term unemployment atrophies skills and makes workers less competitive." The Washington Independent's Annie Lowrey adds, "For every day a person is out of work, not only does he and his family suffer from the effects of lost income, but the chances of his finding work diminish."

• What Caused This Problem  Liberal blogger Matthew Yglesias sighs, "Our failure to start adequately stimulating back in the second half of 2008 (remember back then you heard people say there was no need for stimulus because the policy lags would be too long!) has led to the creation of an enormous backlog of long-term unemployed people who, history teaches, are going to be very hard to get back into the labor market through any kind of ordinary economic process."

• Who Is Most Affected  The Wall Street Journal's Sara Murray reports, "Long-term unemployment has reached nearly every segment of the population, but some have been particularly hard-hit. The typical long-term unemployed worker is a white man with a high-school education or less. Older unemployed workers also tend to be out of work longer. Those between ages 65 and 69 who still wish to work have typically been jobless for 49.8 weeks. ... While blue-collar and construction workers have been battered by the recession, they aren't the only ones hit. Unemployed production workers, including toolmakers, woodworkers and food processors, have been out of work for a median of 38.1 weeks. Unemployed workers whose most recent job was in management, business and financial operations have typically been out of work for 32.3 weeks."

• Recovery Could Leave These People Behind  The Washington Post's Ezra Klein reiterates all the reasons that sustained unemployment causes long-term, sometimes permanent, damage to a worker's prospects. "Unemployment, in other words, lasts. It affects re-employment. And the longer you're unemployed, the worse your next job is likely to be. So the spike in the number of long-term unemployed is the sort of thing that we need to worry about even as we move into recovery, because it implies that recovery, for a lot of people, will not be the return to normalcy that they'd hoped."

• Possible Policy Solutions  The Washington Independent's Annie Lowrey writes, "[Congress] will not extend unemployment benefits any longer than 99 weeks in some states, but will likely continue funding extended unemployment benefits as stimulus. ... What will Congress do if, five years from now, with the recovery well underway, there remain millions of people who simply cannot find work? Job retraining programs and hiring incentives present one partial solution, but if Congress continues to tighten the nation’s fiscal belt, such expensive programs might not be politically feasible."

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