Donald Trump has been savaged by economists and media aligned with establishment candidates for tough positions on trade—including a 45 percent tariff on imports to force China to the negotiating table. Actually, he's got it right. Establishment Democrats and Republicans embrace free trade because it puts free markets first with benefits any decently trained economist should extoll. Unfortunately, trade with China and many nations is hardly market-driven. It hurts U.S. growth and victimizes America's families. Obama's six-year expansion has averaged 2.2 percent annual economic growth and added 13.6 million jobs. Coming off a similar bout with double-digit unemployment, Reagan delivered...