It's quite literally our main export partner. Entire industries in Canada (Airplanes, cars, wood) live and die by US policy.
When Trump was elected the first time, super genius Canadians vowed to fight his trade policy by targeting American politicians in states that trade with Canada, threatening to cut them off. The only problem with that is that Canada is far more dependent on trade with the US than US states are with Canada. <https://np.reddit.com/r/MapPorn/comments/8q9h8i/canadaus_tra...>