A 25 percent tariff on our oil would increase U.S. gasoline prices by 50 cents a gallon — or more. No wonder federal and provincial governments are howling over Donald Trump’s promise to levy a 25 percent tariff on “all” imports from Canada and Mexico on his first day in office. No wonder Alberta Premier Danielle Smith is seeking anti-tariff support from Canada and U.S. governors… Nearly $3.6 billion worth of Canadian goods and services cross the border each day. Canada is the top export destination for 36 U.S. states, and about a third of Canada’s trade with the U.S. is energy. …Whether Trump can or will implement his tariffs on Inauguration Day, January 20 (or later), is being questioned in the U.S. …Trump presumably hopes the oil tariff will encourage more U.S. oil and natural-gas development. But he has yet to explain (if he even knows) how dependent the U.S. is on imports of crude oil used to make gasoline and diesel.