It means that in the world’s biggest economy 12.6 percent of the population – or one person in eight – lives below the poverty line, defined as an annual income around US$10,000 (A$13,200) for an individual or US$20,000 for a family of four.
Children are among some of the biggest sufferers, with 17.6 percent of those under 18 and one in five of those under six living in poverty – a figure higher than any other age group.
Around a quarter of the population of African Americans, and nearly 22 percent of Hispanics are living in poverty.
"Among African Americans the problem correlates primarily to the inner-city and single mothers," said Michael Tanner of CATO Institute, a free-market think tank in Washington.
He noted that African Americans also suffer disproportionately from poor education and lower quality jobs, their median income at US$30,858 a year, is only 61 percent of the median for whites Americans.
The overall ratio, one in eight living in poverty, is virtually unchanged since 2004.
The last significant drop, when it fell to 11.3 percent was in the year 2000 – during Bill Clinton’s presidency but this is the first time since George W. Bush’s presidency that the poverty rate did not increase.
The latest figures did show a decrease of 90,000 people from the 2004 figure, but Census officials described it as "statistically insignificant."
The survey also showed nearly 47 million people did not have health insurance, the fifth year that the figure has increased, despite an economy that is growing.