It’s not just manufacturing. Consider one innovation that could plausibly become a reality in the years ahead: trucks that drive themselves. Over time, that will make the United States economy more productive and raise incomes.

But if you are one of the 1.7 million long-haul truck drivers in the United States, making an average of $42,500 for a job that doesn’t require advanced education, it should be concerning. It’s plausible to imagine a majority of those jobs going away over the next decade, which will be a boon for the countless industries that rely on trucks to bring in supplies and distribute finished goods. That will raise G.D.P., the broad measure of economic growth.

But it would be daunting for any of those drivers who can’t find a job with similar pay, especially during some lag period. The experience with manufacturing does not give much reason for optimism that less-educated workers will have success finding lucrative jobs after a productivity-enhancing innovation the way economics textbooks might predict.

It’s possible that the next wave of productivity gains could come from industries that affect white-collar professionals more than the blue-collar workers who form the core of Mr. Trump’s coalition. Think of artificial intelligence software that could one day replace doctors in diagnosing diseases (or at least make them able to serve more patients at once).

If that happens, the question will be whether those displaced workers can adapt any better than the steelworkers of 30 years ago — and if not, how to deal with masses of white-collar workers who are as disconnected from the modern economy as their blue-collar counterparts seem to be.

Need a labor force boost? Look to immigrants

More people can make more stuff. That is the simple, brutal math behind G.D.P., and it’s the other central challenge of reconciling Mr. Trump’s economic growth ambitions with his other policy priorities. By extension, the more people there are in the United States with the desire to work, the higher the nation’s economic output will be.

One major factor in the sluggish growth of the last few years is that the United States labor force isn’t growing the way it used to. The peak of the baby boom is nearing retirement age. And unlike in the second half of the 20th century, the proportion of women who work is stable, not rising.