Trade is not zero-sum

In the world according to President Trump, trade deficits are among the clearest indication that Americans have become habitual chumps in the global marketplace. The United States sells fewer goods and services than it buys from the rest of the planet, and this is supposedly evidence that Americans are getting rolled. This is the central assumption behind Mr. Trump’s repeated vow to take a meat cleaver to the North American Free Trade Agreement, redrawing the terms of commerce with Mexico. This is the spirit in which he has promised to confront China over its systematic job-killing machine, beginning later this week as he greets the Chinese president, Xi Jinping, at his Mar-a-Lago resort in Florida. But Mr. Trump’s portrayal of trade deficits entails crucial departures from economic reality. In his accounting, international trade is a zero-sum affair, as if every country were jockeying for a share of forever limited amounts of business. An auto part made in Mexico and later included in a finished vehicle destined for a suburban driveway in California represents jobs hijacked from the Midwestern factory that should have employed American hands to build everything. Trade is not zero-sum. Expanded trade has historically tended to support economic growth, which generates more spoils to be divvied up for all. American factories have increased production over the years, in part by drawing on a global supply chain to get what they need. A construction machinery plant in Illinois may buy ball bearings from China, glass displays from South Korea, computer chips from Malaysia and other parts from Mexico, some of them forged with American-made steel.