Beneath a very thin segment of the earth's crust, in northwest Wyoming, is a realm of fire and brimstone. This geological "hotspot" is responsible for the hellish landscape of geysers, hot springs, and bubbly mud that is Yellowstone, the world's first national park, established 1872.

She has been called the United States' greatest gift to the world. Few would argue that Yellowstone was a grander idea than fast food, global warming, and atomic bombs, some of our more recent gifts to mankind. Foreign tourists come to see our parks and we in turn travel to see theirs. The world is thus smaller, and perhaps even a little kinder and gentler, because of an idea called Yellowstone. (next photo)