Donald Trump ascended to the American presidency on the promise of exclusion.\nThe restoration of American greatness, he implicitly argues, depends upon the rejection of certain ideas, unfavorable facts, and unwelcome people.\nALSO READ: The 22 Most Hilarious Twitter Reactions To Black Friday 2018\nTL;DR In this opinion piece, I argue that the threat of a closed U.S.-Canada border could be just the thing to embarass the American government into concessions when it comes to its border policies, particularly with Mexico.\nThe "Border Wall" is the most simplistic representation of this policy of exclusion. Trump's idea, despite evidence, is that a physical barrier would most effectively keep migrants, asylum-seekers, and refugees, whom Trump labels "stone cold criminals," from entering the country.\nThe U.S. border with Mexico is a device of exclusion that Trump has appropriated as a political prop. The president and his administration have repeatedly manufactured crises at the border to bolster claims that America is under siege.\nThis month, for example, debates about migration reached a critical point as a caravan of Hondurans displaced by conflict approached the American southern border, much to the horror of Trump and his followers.\nToday, in response, Trump tweeted that "Mexico should move the flag waving Migrants [...] Do it by plane, do it by bus, do it anyway you want, but they are not coming to the U.S.A."\nMexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries. Do it by plane, do it by bus, do it anyway you want, but they are NOT coming into the U.S.A. We will close the Border permanently if need be. Congress, fund the WALL!\n— Donald J. Trump (@realDonaldTrump) November 26, 2018\nTrump concluded this tweet with a threat: "We will close the Border permanetly if need be."\nThe president has long promised to enforce harsher border policy, but this is the first apparent promise to "close" the U.S.-Mexico border entirely.\nWhile unlikely, the threat underlines Trump's perception of his absolute control over American borders.\nBut Trump is only the most extreme in a long line of domineering American presidents.\nFor decades, the United States has exercised disproportionate influence, if not overt control, over the border policies of its neighbours.\nThe clout of American border policy has become powerful enough to captivate an entire country and control movement even without an explicit directive.\nSuch was the case this year in Canada, where, before and after the legalization of recreational marijuana on October 17th, the threat of harsh treatment for cannabis-consuming Canadians at the U.S. border dominated headlines.\nAfter the U.S. Customs and Border Protection Agency vowed to ban for life any Canadian who even admits to marijuana use, every conversation about legalization included mention of its potential consequences for border crossings.\nThis fear is likely one reason why, according to a recent poll by the Environics Institute, Canadian opinion of the United States is at a forty-year low. A mere 37% of respondants have a positive view of their southern neighbours.\nNow, it's time for both Mexico and Canada to reclaim control of their own borders, if only in the public imagination.\nIf Trump makes good on his threat to permanently stop crossings along the U.S. border with Mexico, Canada should follow with its own promise of a closed border.\nSuch Canadian bluster may just be just the thing to humble Donald Trump and rally the world in opposition to his harsh border policies.\nWhile the economic cost of a closed U.S.-Canada border would be too great to consider seriously, at least as a long-term measure, the mere spectacle of the Canadian government retaliating with its own Trumpian threat could serve to bolster the country's popularity and embarrass the American president into submission.\nThat kind of soft power could give Canada and, by extension, Mexico, more leverage when it comes to North American border policy.\nThe threat would also signal that Canada is able and willing to exercise influence beyond its own immediate circumstances.\nIn the end, perhaps the political force of a few days of a closed U.S.-Canada border would be worth the economic cost.