TORONTO — Ottawa’s mayor, Jim Watson, is upset. He is so upset by President Trump’s unceasing barrage of verbal attacks on Canada, that he did something uncharacteristic for a mayor known to proudly sport a #boringmayor T-shirt: He declined the regular invitation to the July 4 celebrations hosted by the American ambassador, Kelly Craft.

“I don’t feel it’s appropriate for me to go celebrating when a trade war is escalating with every rally the president has,” Mr. Watson said, adding that he hadn’t meant to make a big deal of it, but now that his decision made the news, he wasn’t sorry either. “I suppose I’ll be off the list next year. I’m not going to lose sleep over that,” he said.

Canadians are so inured to being ignored, unappreciated and underestimated by their more powerful American neighbor, it’s a national inside joke that informs the country’s characteristic humility. But, ever since Mr. Trump slapped tariffs on Canadian steel and aluminum and then insulted the Canadian leader as “very dishonest and weak,” Canadians began to experience an emotion more common over the border — patriotism.