From the US Bureau of Labor Statistics (not seasonally adjusted):
Jan 2008 - 144,607,000
Jan 2009 - 140,436,000
June 2010 - 139,882,000
We have to go back to June, 2004 to find a like number to today, 139,861,000. These numbers do not reflect the number of people added to the potential work force during the past six years.