But what might this mean for gadget companies? So many have their products made in that country. Apple, for example.
Trump made a solemn promise: "We're going to get Apple to build their damn computers and things in this country instead of in other countries."
Currently, Apple only manufactures its Mac Pro in the US (specifically in Austin, Texas). On its jobs creation Web site, Apple insists it's responsible for creating and supporting 1.9 million US jobs, as of the end of 2015. It also claims that "thirty-one of the 50 states provide parts, materials, or equipment to make Apple products."
The optics, however, aren't optimum. It may well be that the cardstock for Apple's beautiful letterpress cards comes from Wisconsin, but the image of hundreds of thousands of Chinese workers toiling in difficult conditions in China to make iPhones is more powerful.
It's not entirely clear how Trump would strong-arm Tim Cook. Would he turn up in Cupertino, storm into Cook's office and talk to him about New York values? Would he summon him to Washington or merely send him an iMessage?
Cook has suggested that China's vocational schools actually produce more of the kinds of skilled workers needed for high-tech products. "I mean, you can take every tool and die maker in the United States and probably put them in a room that we're currently sitting in," Cook said in an interview with "60 Minutes" last month. (CNET and "60 Minutes" share a common parent, CBS.) "In China, you would have to have multiple football fields."
Or would Trump hold a special edition of "The Celebrity Apprentice" to make all major US CEOs compete for their jobs? (In order to survive week by week, they'd have to find new ways to market the Trump brand, as well agree to make every product in the US.)
Trump did say that he'd strong-arm Ford CEO Mark Fields by telling him he'd charge a 35 percent tax if Ford continued to manufacture in countries such as Mexico. Presumably, Apple would also be subject to such a draconian sanction.
Oddly, Trump also said he's a "free-trader." However, he doesn't seem to believe American companies should be free to manufacture wherever they choose. "Free trade is good. But we have to do it [force them back to the US]. Or we won't have a country left," he said, undramatically.
His comments about Apple came within a minute of his roughly 50-minute speech ending. But Trump isn't alone in believing that Apple would gain from manufacturing solely in the US.
Immediately after the words about Apple, Trump said he wasn't merely going to make America great again, but "greater than ever before."
Some might believe that, should he win the election, Trump will be the Beltway Berlusconi, though Mr. B didn't quite make Italy great again. Others might muse that he says many truthful things about the way government operates (or doesn't) today.
What's interesting is that Trump how appears to be, well, thinking different. In 2012, he was promoting his book, "Crippled America." Then, he said that he lamented Apple's presence in China.
Trump said: "We have to bring Apple -- and other companies like Apple -- back to the United States. We have to do it. And that's one of my real dreams for the country, to get ... them back. We have a great capacity in this country."
It seems that this particular dream may involve persuasion that is less silver-tongued and more brass-knuckled.