This is the Great Falls of the Missouri in Great Falls, Montana. For you Lewis and Clark buffs out there, this is the falls that they had heard about from the Indians as they worked their way up the river. It is the first of several falls and rapids in the river that required a major portage around the lot of them. This was a miserable task for the Corps of Discovery (think prickly pear cactus while wearing moccasins) which took about a month. If you just imagine the dam spillway not there, you have a good idea of what Lewis and Clark actually saw.