21-May-2011 -- I was surprised to learn that my visit was the first in almost 10 years, because this is one of the easiest confluence points to visit in the whole U.S., as the point lies just to the side of a paved road. Also, this point is quite close to South Dakota's major tourist attractions - Badlands National Park and Mount Rushmore - so it's hard to see why it has not been visited more often.
It was raining intermittently during my visit, but I was able to get photos quickly, without getting my camera too wet.