[nsnick]

Pittsburgh has flights to Seattle. https://www.usatoday.com/story/travel/flights/todayinthesky/...

Also, Northern Virginia is the location of Dulles. Montgomery county would also use Dulles or BWI which has 3 flights per day. Interestingly, with traffic, Washington D.C. is not within 45 minutes of Dulles so Washington D.C. is probably just looking at Reagan which has 1 flight per day to Seattle.

[apcragg]

The silver line will to IAD will be open by the time HQ2 is being built. That puts it ~35mins by Metro when leaving the city. IAD is a huge international airport as well and has much smoother infrastructure than National Airport.