By Sarah Schwartz

Test after test of U.S. students’ reading and math abilities have shown scores declining since the pandemic.

Now, new results show that it’s not just children whose skills have fallen over the past few years—American adults are getting worse at reading and math, too.

The connection, if any, between the two patterns isn’t clear—the tests aren’t set up to provide that kind of information. But it does point to a populace that is becoming more stratified by ability at a time when economic inequality continues to widen and debates over opportunity for social mobility are on the rise.

The findings from the 2023 administration of the Program for the International Assessment of Adult Competencies, or PIAAC, show that 16- to 65-year-olds’ literacy scores declined by 12 points from 2017 to 2023, while their numeracy scores fell by 7 points during the same period.

These trends aren’t unique in the global context: Of the 31 countries and economies in the Organization for Economic Cooperation and Development that participated in PIAAC, some saw scores drop over the past six years, while others improved or held constant.

Still, as in previous years, the United States doesn’t compare favorably to other countries: The country ranks in the middle of the pack in literacy and below the international average in math. (Literacy and numeracy on the test are scored on a 500-point scale.)

But Americans do stand out in one way: The gap between the highest- and lowest-performing adults is growing wider, as the top scorers hold steady and other test takers see their scores fall.

“There’s a dwindling middle in the United States in terms of skills,” said Peggy Carr, the commissioner of the National Center for Education Statistics, which oversees PIAAC in the country. (The test was developed by the OECD and is administered every three years.)

It’s a phenomenon that distinguishes the United States, she said.

“Some of that is because we’re very diverse and it’s large, in comparison to some of the OECD countries,” Carr said in a call with reporters on Monday. “But that clearly is not the only reason.”

American children, too, are experiencing this widening chasm between high and low performers. National and international tests show the country’s top students holding steady, while students at the bottom of the distribution are falling further behind.

It’s hard to know why U.S. adults’ scores have taken this precipitous dive, Carr said.

About a third of Americans score at lowest levels PIAAC is different from large-scale assessments for students, which measure kids’ academic abilities.

Instead, this test for adults evaluates their abilities to use math and reading in real-world contexts—to navigate public services in their neighborhood, for example, or complete a task at work. The United States sample is nationally representative random sample, drawn from census data.

American respondents averaged a level 2 of 5 in both subjects.

In practice, that means that they can, for example, use a website to find information about how to order a recycling cart, or read and understand a list of rules for sending their child to preschool. But they would have trouble using a library search engine to find the author of a book.

In math, they could compare a table and a graph of the same information to check for errors. But they wouldn’t be able to calculate average monthly expenses with several months of data.

While the U.S. average is a level 2, more adults now fall at a level 1 or below—28 percent scored at that level in literacy, up from 19 percent in 2017, and 34 percent in numeracy, up from 29 percent in 2017.

Respondents scoring below level 1 couldn’t compare calendar dates printed on grocery tags to determine which food item was packed first. They would also struggle to read several job descriptions and identify which company was looking to hire a night-shift worker.