The threat of tariffs has put pressure on Canada to clamp down on illegal crossings into the U.S., even as some Canadian officials anticipate a surge in migrants heading the other direction once President-elect Donald J. Trump takes office. ALBANY — For most of the 20th century, the world’s longest international border was practically undefended.

Canadians need to remain calm in the face of U.S. president-elect Donald Trump’s threat to impose 25 per cent tariffs on all imports from Canada, Prime Minister Justin Trudeau said in Halifax on Monday.