The number of Americans in poverty remained largely unchanged at a record 46.5 million. Single-mother

families in poverty increased for the fourth straight year to 4.1 million, or 41.5 percent, coinciding with longer-term trends of declining marriage and out-of-wedlock births. Many of these mothers are low income with low education. The share of married-couple families in poverty remained unchanged at 2.1 million, or 8.7 percent.

By race, a growing proportion of poor children are Hispanic, a record 37 percent of the total. Whites make up 30 percent, blacks 26 percent.

Economic inequality: The numbers also reflect widening economic inequality, an issue President Barack Obama has pledged would be a top priority of his administration to address. Upward mobility in the U.S. has been hurt by a tight job market and the longer-term disappearance of mid-skill jobs due to globalization and automation.

The new census data shows that lower-income households are a steadily increasing share of the population, while middle- to higher-income groups shrank or were flat.

In 2012, households earning less than $24,999 made up 24.4 percent of total households, up from 21.7 percent four years earlier. The share of households earning $50,000 to $99,999 slipped from 31.2 percent to 29.9 percent. Top-income households making more than $200,000 dipped less, from 5 percent to 4.6 percent over that period.

Staying put: The still-weak economy also meant fewer household moves in 2012.

After showing signs of increased migration in 2011, fewer Americans were on the move, many because of few job opportunities or the inability to buy a home.

U.S. migration fell by 0.2 percent in 2012 after edging up the previous year. While the number of longer-distance moves remained steady at 2.3 percent, moves within a county edged lower to 9 percent, particularly among young adults 18-34.

Demographers say that suggests eroding career opportunities and a diminished ability to buy a home. Young adults typically make long-distance moves to seek a new career, while those who make local moves often do so when buying a home.

Homeownership declined for the fifth year in the row to 63.9 percent.

"Many Americans continue to think that a rising tide lifts all boats," said Sheldon Danziger, a University of Michigan economist. "But the bad news is that given the way economic growth trickles down now, the number of poor and disadvantaged will remain high unless we do more to help those in need."

With poverty remaining high, food stamp use continued to climb. Roughly 15.8 million, or 13.6 percent of U.S. households, received food stamps, the highest level on record. Just over half of these households, or 52 percent, were below poverty and 44 percent had one or more people with a disability.

By state, Oregon led the nation in food stamp use at 20.1 percent, or 1 in 5, due in part to generous state provisions that expand food stamp eligibility to families. Oregon was followed by more rural or more economically hard-hit states, including Mississippi, Kentucky, Maine, Michigan and Tennessee. Wyoming had the fewest households on food stamps, at 7 percent.

In 45 states and the District of Columbia, poverty rates remained steady at high levels. Mississippi, the poorest state in the nation, was one of just three states posting increases, from 22.6 percent to 24.2 percent. California and New Hampshire were the others.

In Minnesota and Texas, the percentage of people in poverty declined.

Among the 25 largest metropolitan areas, the Washington, D.C., area had the highest median household income in 2012 at $88,233, followed by the San Francisco and Boston metro areas. The Tampa-St. Petersburg metro area had the lowest median house income at $44,402.