Canada Accounts for Four of Nine Busiest International Routes From US in 2026, Cirium Frequency Data Shows
Why It MattersFrequency rankings reward short, high-turn sectors, so Canada's cross-border city pairs and small-aircraft niches like San Juan–St. Barth outrank long-haul trunk routes that dominate seat-based lists.
Cirium data on annual frequency shows nine routes from the US to an international destination that each have more than 3,000 frequencies per year. Four of the nine connect to Canadian airports and together account for 23,463 departures, or 50.7% of the top nine city pairs. Two of the Canadian entries are New York-area airports to Toronto, and LaGuardia-Toronto leads the ranking. American Airlines, Delta Air Lines, United Airlines, Porter Airlines and Air Canada serve Toronto from one or more of EWR, LGA and JFK. Air Canada recently cut JFK-YYZ amid lower transborder demand.
New York JFK to London Heathrow recorded 7,338 departures in 2026, just behind LaGuardia-Toronto. British Airways, American Airlines, Virgin Atlantic, Delta and JetBlue serve it; United's Newark-Heathrow service is omitted from Cirium's figures. Per OAG, the route ranks 10th among the world's busiest international routes by seats and is the only US route on that list.
Seattle-Vancouver generated 5,371 departures in 2026 over 111 nautical miles (205 km), served by Delta, Air Canada and Alaska Airlines. Chicago-Toronto approached 6,000 annual departures; Envoy Air operates it for American with up to five daily Embraer E170 or Bombardier CRJ-700 flights. Short sectors allow airlines to fly several round trips a day with the same aircraft, which helps explain their high frequencies.
San Juan to Saint Barthélemy (SBH) is projected at 5,103 frequencies in 2026, ranking fifth on Cirium's list and ahead of New York JFK to Paris. Aeroroutes confirms St. Barth Executive and Tradewind Aviation operate it with Pilatus PC-12 aircraft, which seat 10 passengers; the airport's constraints limit it to specialized regional aircraft, so the route would not appear on a list ranked by seats. Houston to Mexico City recorded 3,643 departures in 2026 and Miami to Bogotá 3,231.
