Look at the busiest international routes from Sea-Tac, and look who's number One!! Gets you thinking ....
Busiest International Routes to and from SEA (2015)[44]
Rank City Passengers Annual Change Carriers
1 Vancouver, Canada 562,594 Increase12.9% Air Canada, Alaska, Delta
2 Seoul, South Korea 396,316 Increase22.1% Asiana, Delta, Korean
3 London, United Kingdom 340,364 Increase6.9% British Airways, Delta
4 Dubai, United Arab Emirates 298,476 Increase32.0% Emirates
5 Tokyo, Japan 271,023 Decrease1.1% ANA, Delta
6 Calgary, Canada 257,791 Increase50.0% Air Canada, Alaska, Delta
7 Amsterdam, Netherlands 253,600 Increase1.9% Delta
8 Beijing, China 232,964 Increase10.0% Delta, Hainan
9 Frankfurt, Germany 223,527 Increase34.4% Condor, Lufthansa
10 Victoria, Canada 196,247 Increase6.8% Alaska, Delta
11 Taipei, Taiwan 161,062 Increase4.5% EVA
12 Shanghai, China 159,230 Increase29.3% Delta, Hainan
13 Paris, France 149,734 Increase31.0% Delta
14 Hong Kong 124,300 Increase72.5% Delta
15 Reykjavik, Iceland 117,716 Increase13.0% Icelandair
https://en.wikipedia.org/wiki/Seattle%E2...tional_Airport#Airlines_and_destinations