The kinds of jobs available may not match the distribution of workers' skills, locations or preferences for the kind of work they want to do.
There was a record 6.6 million job openings at the end of March, the Labor Department reported on Tuesday. It suggests that workers feel sufficiently confident in job-market opportunities out there that they're willing to leave their work. Wages rose at almost a 4.5 percent clip the last time the unemployment rate fell below 4 percent.
Job openings have set records over the past few years as businesses have struggled to fill openings.
So where are all the job openings?
The largest job openings increased in professional and business services, construction, transportation, warehousing and utilities, according to the data.
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From a geographical perspective, the number of job openings increased most in the Northeast and Midwest.
That should force employers to push up pay, and many economists expect wage gains will accelerate in the coming months. That should discourage advertising more jobs. That's because it takes more effort - and expense - to find workers when the jobless rate is low, and employers typically have to pay more to lure workers into jobs. More Americans are staying in their jobs rather than switching to new ones for higher pay.
Half of small business owners say they can't find enough qualified workers for open positions, according to a National Federation of Independent Business survey this week.
One signal of worker confidence: The number of workers quitting their jobs rose in March to the highest since 2001.
Another good sign in the same BLS release that these numbers came from: The share of people quitting their jobs continues to trend upward. Over time, it could push up wages.