If tariffs make those imports 25 percent more expensive (or if the flow of oil across the border slows or ceases in response to the new trade barriers Trump wants to erect), prices are likely to rise through the rest of the supply chain, including at the pump.

Wisconsin and other Midwest states rely heavily on oil from Canada, which would be subject to a 25% tariff under Trump's proposal.

Trump has pledged to punish Canada and Mexico for “bringing Crime and Drugs at levels never seen before” by imposing a 25 percent tariff on all imported goods from U.S. neighbors — with no exceptions made for oil and natural gas.