Yes, the reaction will be vastly different based on where in Canada. I did a lot of business in Calgary and in Novia Scotia. In neither place did I get a negative reaction to being from the U.S. However, I’m guessing Vancouver and Toronto would be different. In Calgary, especially, they were more irritated with Eastern Canada than with the U.S.
"They don't want to stay in Canada? Then they should get the bloody hell out!" was one response.
A French teacher, who was born in Quebec and taught in Alberta, and who served in World War II: "I fought for Canada, not Quebec!"
They all seemed to like Americans. A few beers and we were fine with each other.