From the Bureau of Labor Statistics:
In 2007, according to the Census Bureau, 37.3 million people, or 12.5 percent of the population, lived at or below the official poverty level. Although the Nation’s poor were primarily children and adults who had not participated in the labor force during the year, 7.5 million were among the 'working poor'. This level is slightly higher than the level reported in 2006. The working poor are individuals who spent at least 27 weeks in the labor force (working or looking for work), but whose incomes still fell below the offi cial poverty level. In 2007, the working poor rate–the ratio of the working poor to all individuals in the labor force for at least 27 weeks–was 5.1 percent, unchanged from the rate reported in 2006.