That amounts to an historic shift for a nation whose expansion relied on a mobile population. “One thing cannot be denied: America is always on the move,” wrote poet e.e. cummings.

“Migration is a key advantage of the American system historically,” said Kenneth Johnson, senior demographer at the Carsey Institute at the University of New Hampshire in Durham. “The ability of growing areas to attract migrants from a large national labor pool has historically helped the U.S. adapt to changing economic conditions.”

If workers won’t go where the jobs are, it takes longer for employers to fill vacancies. There were 4 million positions open in March, close to a six-year high, the Labor Department reported May 9. The figure is among the job-market barometers that Fed Chair Janet Yellen tracks.

Regional Mismatches

“Low mobility could exacerbate structural imbalances or mismatches based on geographic location of jobs versus workers,” said Harry Holzer, a professor of public policy at Georgetown University in Washington and former chief Labor Department economist.

The mismatches are evident in regional disparities in joblessness. In March, 59 of 372 U.S. metropolitan areas had unemployment rates under 5 percent, while 25 were above 10 percent, the Labor Department reported April 29. Nationwide, joblessness dropped to 6.3 percent in April, the lowest level since September 2008.

The latest Fed Beige Book review of regional economic conditions highlighted the pinch, with six of 12 Fed districts - - Dallas, New York, Cleveland, Richmond, Chicago and Kansas City -- reporting difficulty finding skilled workers.

Truck Drivers

Companies in the district including Texas were paying more to lure truck drivers and oil-field services workers, while employers in the New York, Richmond, and Chicago districts had trouble attracting technology employees, the report said.

Meanwhile McKinzie Weiss, 32, is staying in Las Vegas, which had a jobless rate of 8.7 percent in March, to look for an entry-level job in counseling.