WASHINGTON – The nation’s poverty rate dropped last year, the first significant decline since President Bush took office.

The Census Bureau reported today that 36.5 million Americans, or 12.3% – were living in poverty last year. That’s down from 12.6% in 2005.

The median household income was $48,200, a slight increase from the previous year. But the number of people without health insurance also increased, to 47 million.

The last significant decline in the poverty rate came in 2000, during the Clinton administration. In 2005, the poverty rate dipped from 12.7% to 12.6%, but Census officials said that change was statistically insignificant.

The poverty numbers are good economic news at a time when financial markets have been rattled by a slumping housing market. However, the numbers released today represent economic conditions from a year ago.

The poverty level is the official measure used to decide eligibility for federal health, housing, nutrition and child care benefits. It differs by family size and makeup. For a family of four with two children, for example, the poverty level is $20,444. The poverty rate – the percentage of people living below poverty – helps shape the debate on the health of the nation’s economy.

The figures were released at a news conference by the chief of the Census Bureau’s Housing and Household Economic Statistics Division, David Johnson.

The poverty report comes five years into an uneven economic recovery, and well into a presidential campaign that still has 14 months to go.

Poverty has not been a big issue in the campaign, and political scientists said they doubted the new numbers would change that.

“The poor are politically mute,” a political scientist at the University of Minnesota, Larry Jacobs, said. “What rational politician would listen to the poor? They don’t vote, they don’t write checks, why care?”

Democrat John Edwards has made fighting poverty a centerpiece of his campaign. But, Mr. Jacobs noted, “He’s struggling to raise money and he’s lagging in the polls.”

A political scientist at the University of Chicago, Evelyn Brodkin, said she expects the rising number of people without insurance to get more attention in the campaign.

The share of Americans without health insurance hit 15.8% last year, up from 15.3% the previous year. Mr. Johnson said the increase in the percentage of uninsured was mostly fueled by a decline in employer-provided health coverage.

“It affects people in the middle, and it affects corporations,” Ms. Brodkin said. “Especially those who compete globally, they are really hurting because they have to compete with companies that don’t have huge health insurance bills for their labor force.”

Median household income – the point at which half make more and half make less – was above the U.S. median in 18 states and the District of Columbia, while 29 states were below it. As for individual earnings, in each of the 50 states, women had lower median earnings than men in 2006.

Lyndon Johnson was the last president to launch a major initiative aimed at eradicating poverty, the co-director of the National Poverty Center at the University of Michigan, Sheldon Danziger, said.

Mr. Danziger said low unemployment in 2006 helped lower the poverty rate. But, he noted, the rate was slow to drop despite five years of economic growth.

“For three decades we have had an economy where workers with a high school diploma or less have hardly kept up with inflation,” Mr. Danziger said.

Low-wage workers have been hurt by the nation’s declining manufacturing sector, which has lost more than 3 million jobs since Bush took office.