The 3.5 million Americans who drive trucks for a living may face growing competition for jobs as technology improves and self-driving or autonomous trucks that don't need human operators become more common.
Researchers say a similar wave of automation and robotics displaced most of the 5 million people who lost manufacturing jobs over the past few years. Frustration and fear from that drastic change helped spark an angry movement that upended U.S. politics.
Some experts say it will be years before a significant number of robot trucks are on the roads, as engineers and scientists work on technical, regulatory, and safety concerns while seeking public acceptance of this evolving technology.
But others point out that autonomous trucks already operate in mines, while robotic cars run races up mountains. Automotive and computer firms are working to improve the sensors and processors needed for the task.
"We are not that far from the ultimate vision of a completely self-driving car," said Chan Lieu, a former official of the National Highway Traffic Safety Administration.
Researchers say the same economic pressures that boosted automation in factories also promote robot truckers, who are likely to be less expensive than human drivers. Robots don't need breaks, join unions, ask for raises, demand overtime pay, file lawsuits, or show up with a hangover.
Many Americans say they are worried about the safety of robotic vehicles, but government statistics show 94 percent of road accidents are due to human error. That is causing some worries for the insurance industry, which is trying to figure out how to adjust premiums for an unprecedented, but probably safer, future.
In the meantime, Federal Reserve Chair Janet Yellen expects companies will continue to use more robots. She urges governments and companies to do more to help displaced humans.
"Most economists and policymakers recognize that it's important to provide ways for workers who were harmed by these kinds of developments to be retrained for jobs so that they can succeed in the economy," she said.
Surprisingly, at a time when lost jobs are a major economic and political issue, many high-paying technical positions go unfilled.
Economist Ken Simonson of the Associated General Contractors of America says companies can't find plumbers, electricians, pipefitters and others.
"We are going to continue to see a lot of industries struggling to find already qualified workers or to bring new entrants up to the skill level that they need to get things done," he said.
For many people, apprenticeships offer a way to learn the new kinds of skills that help people find and keep jobs in a workplace of growing technical complexity. Newport News Shipbuilding has been teaching apprentices for nearly a century, and has a strong record of employing the program's graduates.
But researcher David Wiczer of the Federal Reserve Bank of St. Louis says other programs have mixed results.
"Every time you take someone from one occupation to another, the level of risk magnifies,” he said. “It's much safer to switch one employer from the other and do the same thing you've been doing."
In a TEDx talk, MIT economist David Autor says American workers made a big shift from agriculture to manufacturing in the late 1800s and early 1900s.
"We have faced equally momentous economic transformations in the past and come through them successfully," he said.
But workers in this latest economic transition may be in for a bumpy ride, as scholars say previous major changes were wrenching and took many years.