So far, there is little evidence of widespread displacement. Amazon and other companies have hired hundreds of thousands of workers for their warehouses. Manufacturers have added jobs after decades of cuts. The unemployment rate is near a 50-year low, and companies are digging deep into the labor market to find workers — easing education requirements, waiving drug tests and hiring people with criminal records.

Many economists fret that there has not been enough automation. Productivity — the amount of value that employees create, on average, in an hour of work — has been rising slowly. That has helped drag down both economic growth and wages. When workers aren’t more productive, it is harder for companies to pay them more.

Amazon’s announcement on Thursday could be a sign that the strong labor market is finally pushing companies to make investments in both workers and technology to increase productivity.

Big companies, including Walmart and AT&T, have announced their own training programs in recent years. Companies are also raising wages — last year, Amazon committed to paying a minimum wage of $15 per hour — giving them more of an incentive to ensure that those workers are productive.

“A tight labor market really enables workers to be able to demand more,” said J. W. Mason, a fellow at the Roosevelt Institute, a progressive think tank. “When they have to pay higher wages, when they have to struggle to find workers, then they take the steps they need to make sure those workers are worth the money.”

Ardine Williams, Amazon’s vice president of people operations, said the company had more than 20,000 open positions in the United States. In November, Amazon selected Northern Virginia as the site of a second headquarters, after company executives said they needed to look beyond Seattle, its longtime home, to fill its need for talent.

Automation already plays a central role at Amazon’s huge warehouses. Devices tell workers which direction to walk to pick up a package from a shelf. And there are signs that technology is at least easing the company’s voracious appetite for warehouse workers: Last holiday season, it hired fewer temporary workers than in the previous year, and last quarter, its head count was up 12 percent, the lowest rise in years.