In the hierarchy of public lands, national parks by law have been above the rest: America's most special places, where natural beauty and all its attendant pleasures - quiet waters, the scents of fir and balsam, the hoot of an owl, and the dark of a night sky unsullied by city lights - are sacrosanct.

There's one place, and one place only, to see polar bears in America. You have to travel to the country's northernmost point, the very apex of Alaska's North Slope, to the permafrost shores that stretch out on either side from the Inupiat town of Kaktovik.