John Wilbur has seen the industrial slowdown up close. At Roadmaster Group, a trucking company based in Arizona that he runs, business cooled last year as a drop in trade volumes and a slump in the manufacturing sector reduced demand for its big rigs.

Mr. Wilbur had hoped that newly completed trade deals with China, Mexico and Canada would lead to a rebound this year. Then Boeing announced in December that it was shutting down production of its troubled 737 Max aircraft.

“That supply chain is broad and deep, and I think a lot of people don’t even know when they’re being hit by that shutdown,” Mr. Wilbur said.

Now the coronavirus outbreak in China is threatening to further disrupt global trade, with unpredictable effects on the American economy.

“Right when that trade deal gets done, then you throw coronavirus on it, so it’s a little tough to gauge where we are,” Mr. Wilbur said. “Certainly the coronavirus is nothing that anyone budgeted or forecast.”

The data in the jobs report was collected before the coronavirus began to spread, and there have been few signs so far that the outbreak has affected the American economy. Data for the February jobs report will be collected next week, and investors and policymakers will be watching closely for any signs that companies or consumers have become more cautious as a result of the virus.