The constant flow of goods from Asia to the United States was briefly interrupted last month after Hanjin, the South Korean shipping line, filed for bankruptcy, stranding several dozen of its cargo ships on the high seas.

It was a moment that made literal the stagnation of globalization.

The growth of trade among nations is among the most consequential and controversial economic developments of recent decades. Yet despite the noisy debates, which have reached new heights during this presidential campaign, it is a little-noticed fact that trade is no longer rising. The volume of global trade was flat in the first quarter of 2016, then fell by 0.8 percent in the second quarter, according to statisticians in the Netherlands, which happens to keep the best data.

The United States is no exception to the broader trend. The total value of American imports and exports fell by more than $200 billion last year. Through the first nine months of 2016, trade fell by an additional $470 billion.

It is the first time since World War II that trade with other nations has declined during a period of economic growth.