One in seven people lived below the poverty line in 2009 in the world's richest nation.
More than 43 million Americans are currently living below the poverty threshold.
Poverty hit blacks and Hispanics twice as hard as whites and Asians.
Poverty is expected to continue to increase over the next decade.
The number of people living in poverty in the United States leapt by nearly four million last year to 43.7 million, the highest number since the U.S. Census began collecting data on America's poor 51 years ago, officials said Thursday.
One in seven people lived below the poverty line in 2009 in the world's richest nation, or on less than $22,000 a year for a family of four.
That put the poverty rate at 14.3 percent, the highest level since 1994, said David Johnson, head of the U.S. Census Bureau's housing and household economic division.
The number of people without health insurance also reached a sorry record, sweeping past the 50 million mark last year for the first time, Johnson said as the Census Bureau released its annual report on poverty, income and health insurance coverage.
Just under 51 million Americans had no health insurance in 2009, up from 46.3 million in 2008, according to the census report, based on data collected early this year.
"This is the highest number of uninsured since 1987, the first year comparable health insurance data were collected," said Johnson, linking the spikes in both the number of poor and uninsured in the United States to the dull economy and rising unemployment.
Poverty hit blacks and Hispanics twice as hard as whites and Asians, according to the Census data. Around a quarter of African-Americans and Hispanics lived in poverty, compared with 12.3 percent of whites and 12.5 percent of Asians.
Children were also hit hard by the rising rate of poverty, with more than one in five under-18s, or 15.5 million kids from all ethnic groups, living in poverty last year compared to 19 percent, or 14.1 million kids, in 2008.
Ten percent of all kids in the United States, or 7.5 million children, had no health insurance, roughly the same number and rate as in 2008.
While the numbers of Americans living in poverty were high, they fell short of the 45 million that experts had predicted, thanks to median incomes holding steady at just under $50,000 a year and poverty actually falling among senior citizens.
President Barack Obama seized on the slivers of good news among the bad, saying the steps taken by his administration had helped millions of Americans to keep their heads above water in an ailing economy.
"The data released today...remind us that a historic recession does not have to translate into historic increases in family economic insecurity," Obama said.
"Because of the Recovery Act and many other programs providing tax relief and income support to a majority of working families -- and especially those most in need -- millions of Americans were kept out of poverty last year," he said.
"The substantial expansion of the Children's Health Insurance Program (CHIP) helped inoculate our children from the economic distress experienced by their parents, as there was little change in the percentage of children without health insurance."
Ron Haskins, a senior fellow at Washington-based think-tank the Brookings Institution, agreed with Obama that the social safety net had "kept many Americans, children and adults, from falling into poverty.
"Our public programs, especially food stamps, unemployment insurance and Medicaid, have been exceptionally responsive in this recession. They have responded exactly as they were intended to and kept many people out of poverty.
"The story for the elderly, where poverty declined, is in large part a Social Security story, and that's a public program too," he added.
"But any time that child poverty goes up by 1.4 million kids, that's bad news," Haskins told AFP.
The poverty picture was unlikely to improve in the short-term, said Brookings fellow Isabel Sawhill, predicting the recession will cause 10 million more people, including six million children, to join the ranks of the poor by the middle of the decade.