SAT reading scores for graduating high school seniors this year reached the lowest point in nearly four decades, reflecting a steady decline in performance in that subject on the college admissions test, the College Board reported Wednesday.

In the Washington area, one of the nation’s leading producers of college-bound students, educators were scrambling to understand double-digit drops in test scores in Montgomery and Prince William counties and elsewhere.

“Once you hit a certain mark, you want to maintain that,” said Frieda Lacey, deputy superintendent for Montgomery schools. “Don’t think the decline didn’t bother us. It really did.”

Nationally, the reading score for the Class of 2011, including public- and private-school students, was 497, down three points from the previous year and 33 points from 1972, the earliest year for which comparisons are possible. The average math score was 514, down one point from last year but up five from 1972.

The College Board attributed the lower scores to the growing diversity of test-takers, many of whom are less prepared for college-level work or are learning English as a second language.

“The good news is we have more students thinking about college than ever before,” said James Montoya, a College Board vice president. “Anytime you expand the number of students taking the SAT and expand it the way that we have — into communities that have not necessarily been part of the college-going culture — it’s not surprising to see a decline of a few points.”

The disappointing SAT scores come as schools have made major efforts to raise scores on state standardized tests under the 2002 No Child Left Behind law. Some critics of testing say the intense focus on state reading and math exams has taken its toll on higher-order thinking skills.

“We have score inflation on state tests, because that’s what teachers are drilling, and lower performance elsewhere,” said Bob Schaeffer, spokesman for an advocacy group called FairTest.

Locally, average SAT scores were down significantly from 2010 scores reported last year. In Fairfax County, it dropped 10 points, to 1654. In Prince William, it dropped 18 points, to 1490, and in Montgomery, it dropped 16 points, to 1637. The composite score for D.C. public schools dropped seven points, to 1220.

The maximum score is 800 for each subject, including a writing section, and 2400 overall.

Colleges have used the SAT to gauge applicants since 8,040 students took the first exam in 1926. Since then, the voluntary test has been taken by a less and less elite group and has become a closely watched measure of school system performance. However, many factors outside the classroom, including family income and education levels, can influence the results. Schools in poor neighborhoods tend to have lower scores.

For the first time, the College Board said, more than half of all high school graduates — or 1.65 million students — took the exam. That was up from 47 percent in 2010. Test-takers were also more diverse than ever: Forty-four percent were minorities; 36 percent were the first in their family to go to college; and 27 percent did not speak English exclusively.

Whether the decline in SAT reading scores reflects a broader pattern is unclear. This year’s reading scores on the ACT, a rival college admissions test, held steady.

On the National Assessment of Educational Progress, a federal series of tests, 12th-grade reading scores in 2009 rose slightly from 2005. But there was a decline in NAEP scores on that measure since 1992.

Local school systems did not have long-term trend information readily available Wednesday, but many reported significant declines since last year.

Lacey, of Montgomery, said the results may have been influenced by changing demographics, the increasing popularity of the ACT as an alternative test and a decrease in students who take the SAT more than once. Another significant factor is a change in the College Board’s calculation, which now accounts for students who took the SAT for the first time later in their senior year.

Maryland’s largest school system has set a goal to increase the number of students taking the SAT and ultimately to narrow the racial disparity in college enrollment. So far, more than 80 percent of white and Asian students in Montgomery take the test. But for the class of 2011, 63 percent of the county’s black students and 48 percent of Hispanic students took the test — rates largely unchanged from the year before.

Montgomery’s decline in scores followed a surprising 28-point jump in performance last year. The portion of graduates who took the SAT dropped by five percentage points in 2010, to 71 percent.

Many education officials see declining scores as a wake-up call. They say students need more rigorous classes in high school to prepare for college.

“Students are thinking about life beyond the walls of their high schools. But there is a clear indication that some of these students have not taken into account the need for a stronger academic program while in high school,” said William Reinhard, spokesman for the Maryland State Department of Education. “Just taking the SAT is only one step toward their future, and not the first step that should be taken.”