Airlines are slashing capacity as Canadians lose interest in visiting the US.Travel data firm OAG found that bookings on flights from Canada to the US have fallen by more than 70% for every month through to September compared with last year.Filings show airlines have responded by cutting capacity by some 320,000 seats.OAG reported a decline in capacity on flights between Canada and the US every month through to October. For July and August, the decrease was as high as 3.5%."This sharp drop suggests that travelers are holding off on making reservations, likely due to ongoing uncertainty surrounding the broader trade dispute," said John Grant, chief analyst at OAG.United Airlines CEO Scott Kirby told a JPMorgan conference earlier this month the carrier was seeing a "big drop in Canadian traffic going into the US."In February, 500,000 fewer people crossed the land border from Canada into the US compared with the same month last year, a decline of 12.5, according to US Customs and Border Protection data.Some airlines are instead hoping that transatlantic flights will help replace the lost capacity.WestJet, Canada's second-biggest carrier, has canceled routes between New York and Calgary and between Orlando and Edmonton.It's adding more routes to Europe, operating its "most significant transatlantic schedule from Atlantic Canada," said John Weatherill, the chief commercial officer."We have observed a shift in bookings from the US to other sun destinations such as Mexico and the Caribbean, and to transatlantic destinations," a WestJet spokesperson told The Points Guy. "We remain focused on continuing to fly where there is demand."Tourism Economics originally projected a 9% increase in international visitors to the US this year but last month revised that to a 5% decrease, pointing to trade tensions.After President Donald Trump announced auto tariffs on Wednesday, Canadian Prime Minister Mark Carney called them unjustified and a breach of trade deals."The old relationship we had with the United States based on deepening integration of our economies and tight security and military cooperation is over," he said on Thursday.Carney plans to discuss a coordinated response with provincial premiers and business figures on Friday and announce retaliatory measures next week.