The 2004 National Assessment of Educational Progress, known as the nation's report card, also shows that achievement gaps between white and black and Hispanic students remain, but have narrowed.
Education Secretary Margaret Spellings said the results, released Thursday, show that the No Child Left Behind law, President Bush's signature education policy, is helping raise achievement levels.
"We're focusing on policy and getting results and we're getting results," she said in an interview. Among the law's requirements are yearly testing of students in reading and math in grades three to eight, and public reporting of scores for all major groups of students.
"What we have today is some more data that says we're getting better," said Darvin M. Winick, chairman of the National Assessment Governing Board, which oversees the exam, given periodically to 9-, 13- and 17-year-olds to measure what they know.
Last year, 9-year-olds earned their highest scores ever in both subjects since the tests were first given — in 1971 for reading and 1973 for math.
On a scale of 0-500, 9-year-olds scored 208 in reading in 1971, compared with 212 in 1999 and 219 in 2004. In math, they scored 219 in 1973, 232 in 1999 and 241 in 2004.
Most of their improvement came after 1999, the last time this pair of tests was given by the Department of Education's National Center for Education Statistics.