Summary Seattle-Vancouver will rank first in September. It is one of six Canadian and Mexican markets with 100+ monthly one-way flights. Six long-haul airport pairs have triple daily flights.

Delta Air Lines will be the USA's third-largest international operator in September , although second for long-haul flights. Delta plans an average of 231 daily international take-offs in the examined 30 days (double for both ways). Of course, this is a small part of its total operation, accounting for one in ten services.

Delta's number three position is partly because it is a distant third to Canada and Mexico combined, which have a fifth of the USA's international services. Of course, the carrier's partners Aeromexico and WestJet somewhat offset it. With the main exception of SkyTeam-related countries and African nations, Delta is rarely the leading US operator at the international country level.

Which US airports do you think have grown the most to/from Heathrow? Delta's top international routes Analyzing the SkyTeam member's network using Cirium data shows that 176 international routes are planned for September . Some 134 of these will be served at least daily, 40 at least double daily, and 18 at least triple daily. Atlanta, obviously Delta's busiest hub and the world's busiest airport , has the most international take-offs.

Then there's New York JFK, Minneapolis, Detroit, Seattle, Salt Lake City, New York LaGuardia, Boston, Los Angeles, Miami (really: to Havana), Honolulu, Portland.