According to Frommers, American tourism is already being hammered.

http://www.frommers.com/tips/miscellaneous/the-travel-press-is-reporting-the-trump-slump-a-devastating-drop-in-tourism-to-the-united-states#.WK-ZaHKDkZv.twitter

In addition to tourism this is going to seriously damage the economies of those American border towns that cater to Canadians crossing over to buy gas, groceries and the like.