ASHINGTON, Sept. 24 — The number of poor people in the United States rose by about 1.3 million last year, while household income declined significantly as the country struggled through a recession, the Census Bureau said today.

The ranks of the poor increased to 32.9 million in 2001, up from 31.6 million in 2000. And median household income fell 2.2 percent, to $42,228, meaning half the households had income above that figure and half below, the bureau said.

In percentage terms, the nation's poverty rate rose to 11.7 percent in 2001 from 11.3 the year before. Before rising last year, the poverty rate fell for four straight years.

"Like the last year-to-year increase in poverty in 1991-1992 and the last decrease in real household income in 1990-1991, these changes coincided with a recession," said Daniel Weinberg, chief of the Census Bureau's Housing and Household Economic Statistics Division.

The "poverty" threshold, in official terms, was $18,104 for a family of four; $14,128 for a family of three; $11,569 for a family of two, and $9,039 for individuals.

The poverty rate and the actual numbers of the poor rose among various population groups, including families, unrelated individuals, non-Hispanic whites and people 18 to 64 years old, the Census Bureau said.

"Like the increase in poverty, the decline in real median household income between 2000 and 2001 coincided with the recession that started in March 2001," Mr. Weinberg said. "The decline was widespread. With the exception of the Northeast, where income was unchanged, all regions experienced a decline, as did each of the racial groups."

While today's information was somewhat gloomy, it did not come as a surprise. Many analysts had predicted such findings in view of the recession. The poverty rate is calculated annually by the census agency.

Even though the experts who compiled the statistics considered factors like food stamps and other noncash benefits, calculating the human suffering and discouragement spawned by poverty might be all but impossible.

The reports cited in the bureau's announcement today, "Poverty in the United States: 2001" and "Money Income in the United States: 2001," are available on the Census Bureau's Web site: www.census.gov. Together, they offer a treasure trove for devotees of numbers and statistics, although the figures must be read with certain caveats.

For instance, the ratio of female-to-male earnings reached an all-time high of 0.76 — seemingly encouraging news, in view of the fact that women's earnings have long lagged behind men's, generally speaking.

Indeed, the real median earnings of women 15 and older who work full time went up for the fifth year in a row, to $29,215. Because men with similar experience did not experience a similar statistical change in earnings, the female-to-male earnings gap was narrowed, even though men's earnings remained higher.