By Jeffrey J. Selingo, author, for The New York Times

When the German engineering company Siemens Energy opened a gas turbine production plant in Charlotte, N.C., some 10,000 people showed up at a job fair for 800 positions. But fewer than 15 percent of the applicants were able to pass a reading, writing and math-screening test geared toward a ninth-grade education.

“In our factories, there’s a computer about every 20 or 30 feet,” said Eric Spiegel, who recently retired as president and chief executive of Siemens U.S.A. “People on the plant floor need to be much more skilled than they were in the past. There are no jobs for high school graduates at Siemens today.”

Ditto at John Deere dealerships, which repair million-dollar farming machinery filled with several dozen computers. Fixing tractors and grain harvesters now requires advanced math and comprehension skills and the ability to solve problems on the fly. “The toolbox is now a computer,” said Andy Winnett, who directs the company’s agricultural program at Walla Walla Community College in Washington.

These are the types of good-paying jobs that President Trump, blaming trade deals for the decline in manufacturing, has promised to bring back to working-class communities. But according to a study by Ball State University, nearly nine in 10 jobs that disappeared since 2000 were lost to automation in the decades-long march to an information-driven economy, not to workers in other countries.