WASHINGTON – The U.S. poverty rate decreased to 11.3 percent of the population last year, its lowest level since 1974, the Census Bureau reported Tuesday.

Meanwhile, median household income leveled off at $42,148 in 2000, after increasing for much of the 1990s. Accounting for inflation, the median household income fell slightly from the record high of $42,187 in 1999.

Nationwide, 31.1 million Americans lived in poverty, down from 32.3 million, or 11.8 percent of the population in 1999.

At the same time, Maine’s poverty rate dropped 0.6 percentage point, from 10.4 percent to 9.8 percent, the Census Bureau said. New Hampshire’s rate decreased 2.5 percentage points to 6.3 percent.

“The drop in the poverty rate belongs to a larger story of economic recovery since the last recession,” said Daniel Weinberg, chief of the bureau’s division of housing and household economics statistics. “Poverty rates tend to peak soon after a recession.”

Analysts, though, have cautioned not to consider these figures an up-to-date barometer of the country’s financial health.

The figures come from a survey of 50,000 households taken in March and relate to questions about income and poverty status for 2000. As a result, the survey would not reflect recent turmoil in the economy.

The record low poverty rate was 11.1 percent, set in 1973.

Since 1993, Weinberg said, poverty rates have also declined along most racial, ethnic and age groups.

The poverty rate for Americans under 18 was 16.2 percent, down for the third straight year, the bureau said. Even so, people under 18 still had a higher poverty rate than those in any other age group.

The poverty threshold differs by the size of the household. For instance, in 2000, a family of four was considered to be impoverished if the household earned $17,603 or less a year.

Median income refers to the point at which half of households earn more and half earn less. The last time there was a decrease in median household income was in 1992-93.

Still, Weinberg stressed that the latest decrease in overall median household income was not statistically significant.

Other findings:

. The poverty rate of 22.1 percent for blacks set a record low, though it still lagged far behind that of non-Hispanic whites (7.5 percent). The median income for black households was $30,439, also a high.

. For the first time in four years, men working full time year-round experienced a decline in real median earnings, from $37,701 in 1999 to $37,339 in 2000. Earnings for women increased slightly to $27,355.