The labor force should have increased by around 4.2 million workers from December 2007 to December 2010 given working-age population growth over this period, but instead it has fallen by 246,000. This means that the pool of missing workers now numbers around 4.4 million.
If just half of these workers were currently in the labor force and were unemployed, the unemployment rate would be 10.7% instead of 9.4%. None of these workers is reflected in the official unemployment count, but their entry or re-entry into the labor force will contribute to keeping the unemployment rate high. –From Heidi Shierholz’ analysis of the latest unemployment report.