A crowd in Buffalo chimed in to sing the Canadian national anthem before an N.H.L. playoff game. That presented a contrast to ongoing U.S.-Canada tensions.

For about two and a half minutes inside the KeyBank Center in Buffalo, N.Y., on Tuesday night, the simmering Canada-U.S. tensions seemed to melt away just a bit, all thanks to the stirring voices of some 19,000 people in the stands. Read More