Interesting that a letter sent from NYC will take 1 day longer to arrive in Fairbanks or Juneau vs what I presume are the oil fields on the eastern north slope near ANWR. Yet a letter sent from Fairbanks takes a day longer to arrive in the same oil fields area than the rest of the interior and the quite remote NW.
Some odd things can happen when the destination is close (relatively speaking), but not too close.
A recent example is USPS Parcel Select packages from the SF Bay area to Sacramento being routed through Los Angeles (!). I have seen this twice in the past couple months. This does not happen with Priority Mail.