If all those so-called discouraged jobseekers had remained in the labor force, August's jobless rate of 8.1 percent would have been 10.5 percent.
The jobs crisis spurred the Federal Reserve last week to launch a new bond-buying program and promise to keep it running until the labor market improves. It also poses a challenge to President Barack Obama's re-election bid.
The labor force participation rate, or the proportion of working-age Americans who have a job or are looking for one has fallen by an unprecedented 2.5 percentage points since December 2007, slumping to a 31-year low of 63.5 percent.
"We never had a drop like that before in other recessions. The economy is worse off than people realize when people just look at the unemployment rate," said Keith Hall, senior research fellow at the Mercatus Center at George Mason University in Arlington, Virginia.
Continue Reading: America's hidden unemployed: too discouraged to count | Reuters