Polar night is from October 27 to February 15, just under 4 months. Thus, while the places with 6-month days and nights are not in any country, there are countries and cities where most of the year is either 24-hour days or 24-hour nights. read more
Only the North and South poles actually have a 6-month day and 6-month night. However, some countries come close. Antarctic claims are held in abeyance, so if those are excluded, the highest-latitude places actually in countries are in the northern hemisphere. read more
Only the North and South Pole have a 6 month period of continuous daylight and nearly 6 months of night. Parts of some countries extend above the Arctic Circle and can have more than 24 hours of sunlight in summer (midnight sun), and more than 24 hours of night during the winter (polar night). read more