China’s exports surged even more than expected in July, as Chinese companies raced to ship goods to Southeast Asia and other regions, often for onward shipment to the United States, before President Trump could raise tariffs on imports.

China’s overall exports were up 7.2 percent in July from the same month last year, while imports were up 4.1 percent. Its exports to Southeast Asia and Africa, key regions for reshipment to the United States, rose more than twice as fast as its overall exports. China’s exports to the European Union, its main alternative to the American market, were also up very strongly.

By contrast, China’s exports directly to the United States were down by more than a fifth in July, as buyers in the United States appeared wary of paying Mr. Trump’s extra 30 percent tariffs.

China’s economy relies heavily on exports, in part because a steep fall in apartment prices in recent years has ruined the personal finances of millions of households, leaving them unable to afford the vast quantities of goods pouring out of China’s factories.

China’s trade surplus reached almost $1 trillion last year, with its surplus in manufactured goods equal to a tenth of the country’s entire economic output.

Ever since senior American and Chinese officials reached a truce on tariffs in Geneva in mid-May, the United States has been charging an extra 30 percent tariff on imports from China. That is in addition to existing tariffs, notably the 25 percent tariff that Mr. Trump had imposed on roughly a third of American imports from China in his first term.