Places far away from any major airport or Highway would hold out for a very long time. Remote places like parts of Montana, the Dakotas, the UP in Michigan, the smaller Hawaiian islands.
- You'd have hundreds of cruise ships out during the initial outbreak.
- The Navy's of the word would be pretty well off because of the numbers of ships that will be underway
- Mongolia
- Many parts of Sub saharan Africa
- Isolated parts of Australia
- the greater NW part of WA state..
- North Korea
- People stuck on the runways of many airports and in the planes in holding patterns waiting to land
of course this is all my speculation