On September 16, the U.S. Census Bureau released the report Income, Poverty, and Health Insurance Coverage in the United States: 2009. The report found that the number of uninsured Americans increased from 46 million in 2008 to 51 million in 2009, accounting for 16.7 percent of the population.  In addition, 2009 was the first year that the number of insured Americans declined since the Census Bureau started collecting these data in 1987. 

From the report:

This report presents data on income, poverty, and health insurance coverage in the United States based on information collected in the 2010 and earlier Current Population Survey Annual Social and Economic Supplements (CPS ASEC) conducted by the U.S. Census Bureau. Summary of findings: 1)The median household income in 2009 was not statistically different from the 2008 median in real terms. 2)The poverty rate increased between 2008 and 2009. 3) The uninsured rate and number of people without health insurance increased between 2008 and 2009.

Full Report: Income, Poverty, and Health Insurance Coverage in the United States: 2009 (PDF | 1.09 MB)  

U.S. Census Bureau. (2010). Income, povery, and health insurance coverage in the United States: 2009. Denavas-Walt, C., Proctor, B., Smith, J.