RALEIGH — The collapse of middle-class jobs since the turn of the 21st Century has been worse in North Carolina than the rest of the country, a university economist says in an upcoming book forecasting the state’s future.

While the number of middle-class jobs rose by 6 percent nationwide between 2001 and 2015, there were 5 percent fewer in North Carolina, North Carolina State University’s Michael Walden found. Meanwhile, high- and low-paying jobs each increased in North Carolina by more than 25 percent, up to three times faster than the rest of the country, he said Wednesday.

The economic pressure on the middle class is helping pull apart social cooperation because as jobs paying a middle-class wage disappear, people see less chance of getting ahead, Walden said.

“Clearly, what’s been happening to our economy, ‘the hollowing-out’ as well as other things, has political implications,” Walden said.

More than two dozen communities from Morehead City to Boone have seen middle-class jobs paying between $45,000 and $69,000 decline during the period Walden studied. The effect was worst in the Asheville, Charlotte, Wilmington and Winston-Salem areas and across 20 rural counties in the state’s mountains and western Piedmont.

A key reason is the greater reliance of mountain and western Piedmont areas on textile and apparel manufacturing, which have largely been boarded up in recent decades, Walden said.

“The studies that have been done in North Carolina of people who have lost jobs, particularly who have lost jobs in the textile and apparel industries, show that they don’t get retrained, they don’t get reskilled. They end up taking lower-paying jobs than they had,” Walden said in an interview.

And while North Carolina workers saw their per capita incomes climb throughout the 20th Century toward the national average, those wages compared to the rest of the country have fallen back to levels seen in the early 1980s, Walden found.

Walden’s research is further indication that improving unemployment rates mask the fact that in many communities there are too few jobs paying enough to support a family, said Maureen Berner, who teaches municipal officials about public administration at the University of North Carolina at Chapel Hill’s School of Government. The stress also has shown up through an annual, double-digit growth in need for food distributed by nonprofits like churches and food banks, which usually require proof of income and resources, she said.

“If the line is longer, there are more people in need,” she said. “We are effectively seeing indications of the disappearance of the middle class.”

The findings also could help explain why even though several economic indicators improved during former Republican Gov. Pat McCrory’s term, his re-election campaign last year seeking credit for a “Carolina Comeback” didn’t fully catch on with voters.

“The ‘Carolina Comeback’ discussion occurred in a political context, with Republicans taking credit for policies that appeared to boost North Carolina’s economic growth in recent years,” said John Hood, a political commentator and president of the conservative John William Pope Foundation. “Walden’s work should remind everyone that most of the causal factors for North Carolina’s economic performance over the past few decades are either external to state government or not fully understood.”

McCrory didn’t respond to emails sent to his private accounts.