U.S. retailers and manufacturers, faced with sky-high tariffs on Chinese goods, are pausing and reducing shipments from China. The pullback is expected to hit West Coast ports within days.

The number of containers scheduled to arrive at the Port of Los Angeles is anticipated to drop more than 35% next week compared with the same period last year, data from the port shows. And a quarter of the ships that had been scheduled for May have canceled because of light volume, said Gene Seroka, the port’s executive director.

Seroka attributed the expected downturn to President Donald Trump’s tariffs — most notably, tariffs on Chinese goods, many subjected to levies of up to 145%.

The Port of Los Angeles, which handles the largest volume of container shipments from China, reported a surge of imports in recent months as companies tried to get ahead of the tariffs Trump had long promised. In April, as Trump’s trade war with China escalated and retailers’ fears about broad tariffs came to pass, large importers scaled back shipments, Seroka said.

Some of the 125,000 importing companies that rely on the Port of Los Angeles, including big-box retailers and home improvement stores, have halted nearly all of their imports from China, he added, referring to conversations with the firms.

“Now, major importers are saying, ‘I’m going to wait, hit the pause button,’ ” Seroka said. “I don’t see any quick change.”

It takes about two weeks for vessels to travel to the West Coast from China — about how long ago the tariff escalations between the United States and China kicked in.

At the Port of Long Beach, which also processes a significant amount of goods from China, the number of vessels arriving dropped 38% this week from last week, said Mario Cordero, the port’s chief executive. Fewer stops indicate that volume is already starting to decline, he said, in a clear reversal from the months leading up to May.

“The trajectory is not good,” Cordero said. While there might be some fluctuation in import data in the coming weeks, the port predicts cargo activity will decline 20% in May compared with a year ago. As of Tuesday, at least 30 ships scheduled to sail through June have canceled, he added.

Census Bureau data released Tuesday showed a surge in U.S. imports starting last fall, from $268 billion at the end of October to $343 billion at the end of March, reflecting a push by major American companies to buy goods ahead of anticipated tariffs. The U.S. trade deficit for goods widened in March to a record high.

Finished consumer goods that wholesalers and retailers import directly from China make up the bulk of the items expected to be most affected at the Los Angeles and Long Beach ports, said Jason Miller, a professor of supply chain management at Michigan State University.

“This is just a pure demand destruction scenario at the moment, where there’s just not as much stuff coming in,” Miller said.

East Coast ports are likely to see a similar drop in shipping volume a couple weeks after the West Coast decline, Miller said.

If the downturn in imports is sustained, the effects on employment and economic growth are likely to extend far beyond the ports themselves. Moving fewer containers means not just less work for dockworkers, but also subdued demand for trucking and warehouse jobs.