Trump plans 25% tariffs on Canada, Mexico. What will it mean for Iowa's economy, farmers? Last time it left a $2 billion dent

Trump underscored his intention to use tariffs, a tax on foreign goods, as a tool of international economic policy and an increasingly vital source of government revenue.

China has strengthened trade with Latin America at the expense of the U.S. But Donald Trump, who threatens to raise tariffs on Mexico, could upend those ties.