Trade wars won’t sharply curtail economic activity, unless they cause businesses to lose confidence, said Spencer Dale, chief economist for BP, the energy giant. The bigger problem, he said, is that trade wars could “eat away at trend growth” by reducing G.D.P. by a fraction of a percent a year. That might not seem meaningful in any given year, but compounded over a decade or two, it could leave the economy noticeably short of what it might otherwise have achieved.

The Fed chairman, Jerome H. Powell, has also noted those risks. “Changes in trade policy could cause us to have to question the outlook,” he said on Wednesday at a European Central Bank conference in Portugal.

Still, the United States remains more insulated from a trade shock than other countries. Exports account for just 12 percent of American gross domestic product. That’s the lowest share among the 35 members of the Organization for Economic Cooperation and Development, a group of industrialized countries. By contrast, the figure is 31 percent in Canada, 37 percent in Mexico and 44 percent in the European Union.

In the United States, consumer spending accounts for nearly 70 percent of G.D.P. And recent surveys and other data show that people are bullish about the economy’s trajectory, according to Ian Shepherdson of Pantheon Macroeconomics. Owners of small businesses are also confident — about their own prospects and about the overall economy.

When Mr. Shepherdson put out a note to clients on May 14 highlighting the possibility of 5 percent growth in the quarter, he was quick to add that his forecast looked outlandish. “I was being tongue in cheek, looking at what would happen if everything goes right,” he said. “But it’s become more like the base case.”

Despite the improving consensus, Mr. Shepherdson said the quarter’s pace “is not sustainable,” but he does expect consumer spending to be solid in the second half of the year.

Sean McCartney, an executive vice president at Radial, a fulfillment and logistics business, agrees, and he’s putting his money to work. Radial will hire about 24,000 temporary workers later this year for the company’s fulfillment centers, call centers and warehouses to prepare for back-to-school demand and the holiday shopping season. That’s up by roughly 1,000 from last year.