More than one in three children under 18 living in the District is poor, according to annual U.S. Census figures released yesterday.

Nationally, the poverty rate has been declining in the past few years, but that has not been the case in the District.

About 35.6 percent--or 38,366--youths younger than 18 lived in poverty in the District in 1996, according to the report, which uses a combination of food stamp records, data from federal income tax returns and census figures to determine who is poor. When compared with the 50 states, D.C.'s child poverty rate ranks highest.

Mayor Anthony A. Williams yesterday called it "problematic" to compare the District to states, but he said that the "census remains a valuable tool in receiving federal funding."

Experts consider it misleading to compare statistics on the District, a small and entirely urban jurisdiction, with states that have urban, rural and suburban populations. The estimates are important, said Census Bureau statistician Paul Siegel, because they are used in administering federal programs and allocating federal funds to local jurisdictions, including the District.

In Virginia, the rate of children younger than 18 living in poverty in 1996 was 16.5 percent, and in Maryland it was 14.1 percent. Nationally, the percentage was 20.5.

"Despite the fact that the economy is nominally good, the economy for low-skilled people is bad and D.C. has a shortage of low-skilled jobs," said Liz Siegel, co-founder of D.C. Action for Children, a children's advocacy group.

Liz Siegel, no relation to the census statistician, said: "We've always had a small middle class. We have a lot of fairly wealthy people, and then we have a lot of very low income residents. Our school system and public safety issues have chased the middle class out to the suburbs."

The mayor has said that improving services to children, especially those living in poverty, is one of his top priorities. He and two D.C. council members recently began a program designed to address the needs of District children in a comprehensive fashion.

The overall poverty rate in Maryland in 1996 was 9.6 percent and in Virginia 11.3 percent. Nationally, the percentage was 13.7.

Compared to the 50 states, the District ranks as one of the poorest. The census figures from 1996 actually show the District as the worst in the country, with 21.1 percent living in poverty. But census officials said that the estimated percentage of people living in poverty in four states--West Virginia, Louisiana, Mississippi and New Mexico--is so statistically close that none of the four or the District can definitively be called the worst.