Mr. Trudeau’s apology came less than two weeks after a gunman opened fire in a Pittsburgh synagogue, killing 11 worshipers, and at a time when anti-Semitism is rising across North America. It was not lost on many that it was delivered the day after an American election campaign marked by refugee-bashing.

“The rhetoric we are hearing across the border is very similar to the rhetoric we heard in the 1930s — the vilification of the other, the vilification of the press. It’s really scary,” said Danny Gruner, who attended Wednesday’s apology with his mother, Ana Maria Gordon, the sole survivor of the St. Louis living in Canada today.

Ms. Gordon, who met with Mr. Trudeau privately, was surrounded by many of her great-grandchildren and grandchildren.

Last week, Mr. Trudeau apologized to a British Columbia First Nation for the government’s treachery in inviting six Tsilhqot’in chiefs to peace talks 150 years ago. Instead of talking, the government arrested them, put them on trial and hanged them.

He has also apologized to Omar Khadr, the only Canadian who was held at the United States military base at Guantánamo Bay, Cuba. He emotionally apologized to gay members of the army, the police and in public service who were persecuted — some even imprisoned — because of their sexual orientation.

And he tearfully said sorry to indigenous people in the province of Newfoundland and Labrador, where for much of the 20th century indigenous children were torn from their families and compelled to attend boarding schools, where many were abused.

“You will not remove the guilt from the perpetrators of the horror,” Mr. Gruner said. “But at least you can come to terms with what the country was at the time, and try to understand where we are at this particular time and where we want to be.”