By covered wagon and jetliner, from East Coast to West, Rust Belt to Sun Belt, Americans’ propensity to be on the move – to new jobs and new places – has historically provided the economy with a critical dose of oomph.

But as fewer and fewer Americans are loading up the moving van in search of opportunity, that advantage may be slipping away. In recent years, economists have become increasingly worried that a slide in job turnover and relocation rates is undermining the economy’s dynamism, damping productivity and wages while making it more difficult for sidelined workers to find their way back into the labor force.

“It’s possible that one reason people aren’t changing jobs is because they’ve all found jobs that are great for them and they’re happy,” Betsey Stevenson, an economist at the University of Michigan and a former member of President Obama’s Council of Economic Advisers, said. “But the other possibility is that people stay in jobs that aren’t as good for them because they’re terrified of changing, and that’s bad for the overall economy.”

Staying put can mean that workers are not moving to jobs where they would be more productive. At the same time, many are forgoing the raises and ascents on the career ladder that often come with a job switch. Fewer openings can also have a ripple effect, shrinking the bargaining power of workers in general, making it tougher to ask for a bump up in pay.