I sent out a round of postcards to get postmarks for my growing collection. The first one to make it back to me is from the remotest post office in the US. Anaktuvuk Pass is a few degrees north of the Arctic Circle. The population is 250 people, but they have an airport because there are no roads and they're quite far from the coast. Wikipedia tells me their name means Caribou Droppings, so I just drew a caribou, and will paint it now that it's back.
At 68* polar night lasts 20 hours, and at the north pole (90*) it lasts from September to March. And Anaktuvuk is at 70*. So, I don't know whether 1/22/2012-2/2/2012 is overnight there, although I intuit that it's not.