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.

The Canadian government made clear its beefing up its border security apparatus after President-elect Donald Trump threatened to impose sweeping

The strained relationship between the president-elect and Canadian Prime Minister Justin Trudeau stands to complicate Canada’s ability to navigate a second Trump term.