The president's central claim — that the United States has a trade deficit to Canada — is wrong. While there is a trade deficit in merchandise goods, the United States has a larger trade surplus on services. The Office of the U.S. Trade Representative, which is part of the executive branch, reports a net $8.4 billion U.S. surplus in trade with Canada in 2017, and other federal agencies have similar calculations.
This is not the first time Trump has propounded this whopper. When he met with Canadian Prime Minister Justin Trudeau in March, he told his northern counterpart he was unhappy about the deficit. Trudeau pushed back, but the president was undeterred, boasting at a fundraiser later that though he "didn't even know," he "just said, 'You're wrong.'" White House Press Secretary Sarah Huckabee Sanders said Trump was not incorrect because he was only thinking of goods, not services.