Donald Trump is í70s Man. He loves beauty pageants. He puts ketchup on his steak. And he thinks the surest signs of economic might are thriving smokestack industries churning out the raw materials for skyscrapers and locomotives.

Businesses and investors everywhere are on edge as Trump, himself a lifelong builder, is now attempting to translate his industrial-era economic worldview into action. Trump has promised to impose tariffs of 10% on all aluminum imports to the United States, and 25% on all steel imports. The stock market has wobbled on that news, and now Trumpís top economic adviser, former Goldman Sachs president Gary Cohn, has quit in frustration over Trumpís tariffs. Investors have viewed Cohn as the strongest bulwark against economic nationalism that could trigger damaging trade wars, and his departure will undoubtedly unnerve markets further.

ďIf you donít have steel, you donít have a country!Ē Trump tweeted, in all caps, on March 2. Itís also true that you donít have a country, or at least a prosperous country, if you donít have software, data centers, accounting firms and teachers. Yet Trump talks little, if at all, about the segments of the economy that are the biggest source of wealth and power these days. And he seems ready to risk damaging the economy to protect industries that represent a small and declining share of American production.