[george76]

In January 2009, when he took office, there were 80,507,000 Americans not in the labor force. Thus, the number of Americans not in the labor force has increased by 10,102,000 by September 2013.

according to BLS, Americans not participating in the labor force climbed to 90,609,000 by September 2013.

Thus, the number of Americans not in the labor force has increased by 10,102,000

http://cnsnews.com/news/article/terence-p-jeffrey/90609000-americans-not-labor-force-climbs-another-record

[george76]

Record 92,269,000 Not in Labor Force; Participation Rate Matches 36-Year Low. [ August, 2014 ]

http://www.cnsnews.com/news/article/ali-meyer/record-92269000-not-labor-force-participation-rate-matches-36-year-low

[Wyatt's Torch]

Okay that's different from "workforce has shrunk". Total employed has gone from 133,976,000 in January 2009 to 139,435,000 today (which is a record high. Also of note the recession low was 129,655,000 in February 2010) so the workforce has grown by 5.5 million over the timeframe you reference.

Here is the chart for that timeframe: