Note this article:
Livengood: How Michigan's Trump country would get hit harder in a Canadian trade war
Here is my summary:
President Trump said we don’t need any oil or gas from Canada. This is not true. There are as many as 1.3 million rural residents in Michigan living on propane gas and Michigan is the nation's No. 1 consumer of propane. The majority of Michigan's propane supply comes from Canada. Propane costs would increase overnight if that supply were disrupted or a tariff imposed.
Likewise, oil refineries in the Upper Midwest are largely geared toward refining heavy crude oil from western Canada that flows into the country through multiple pipelines. It would be difficult to switch to light Texas oil. This would impact the Marathon refinery in Detroit as well as two in Toledo that supply unleaded gas, diesel and jet fuel to Michigan. (both Toledo refineries account for 43% of Michigan's motor fuel supply.)
Besides hurting households, dramatically rising gasoline and home heating costs could become a political issue since there is an open U.S. Senate seat in Michigan next year.
Source: How Michigan's Trump country would get hit harder in a Canadian trade war
Frank Zaski