Trump Will Impose 25 Percent Tariffs on Canada and Mexico on Tuesday

“Our American automakers, who invested billions in the U.S. to meet these requirements, should not have their competitiveness undermined by tariffs that will raise the cost of building vehicles in the United States and stymie investment in the American work force,” said Matt Blunt, the president of the American Automotive Policy Council, which represents General Motors, Ford Motor and Stellantis, the maker of Jeep, Chrysler, Ram Trucks and other brands.

Auto companies have said they cannot quickly relocate production to the United States and will have to pass the tariffs on to customers, adding thousands of dollars to car prices. “You don’t have to be an expert in autos to see how detrimental this would be,” said John Helveston, an assistant professor at George Washington University who teaches engineering management.

The prospect of tariffs has also created intense uncertainty for small business owners. Logan Vanghele, 28, who runs a small company that sells lighting and equipment for aquariums, all of which is made in China, said that he was facing roughly $25,000 in tariffs on a large shipment of products coming in from China.

When the $120,000 shipment left Yantian Port in southeastern China in January, just days before Mr. Trump’s inauguration, Mr. Vanghele had no idea that it might face such fees. After Mr. Trump announced last week that an additional 10 percent tariff on Chinese goods would take effect on Tuesday, Mr. Vanghele immediately called the logistics company that was handling the cargo.

He pleaded with them to unload his container at a port in Norfolk, Va., where it stopped on Friday, instead of traveling on to Boston, hoping he could bring the products in before the tariffs went into effect. While it is possible that Mr. Trump’s new tariffs will include an exemption for goods that are already on the water, there is no guarantee.

“Even if I’ve got to pay an absurdly high amount for it to get trucked over, it’s not going to come close to what the tariffs are,” Mr. Vanghele said. “I’m basically in Hail Mary mode.”

Reporting was contributed by Joe Rennison, Minho Kim, Paulina Villegas, Rebecca F. Elliott, Jack Ewing and Danielle Kaye.