evidence: Tariffs Undermine Jobs. If tariffs remain in place, these small changes in costs and prices become permanent and begin to spread. Why? Take the example of steel: The U.S. produces most of the steel we consume, but when we impose a tariff on imported steel, domestic producers of steel see an opportunity to raise their own prices. As a result, the cost of producing things made with steel in the U.S. increases. This is true in any production chain affected by tariffs: Shoes become more expensive to produce if we levy a tariff on leather; grocery stores will see their costs increase if we levy tariffs on fresh produce; books and newspapers become costlier to produce if we tax imports of paper. In markets where substitutes are not readily available – avocados in winter, for example, or gasoline – consumers will see prices rise almost in lockstep with the tariff. [...] This is the ultimate lesson of our country’s last bold experiment in protectionism: Tariffs, even more than other forms of taxation or government interference in the marketplace, create dysfunctional incentives that distort costs and prices throughout the economy. They tend to shore up yesterday’s industries at the expense of tomorrow’s industries, an illusion of "protection" from an underlying economic reality that cannot be denied forever.