Bridges part 2

I left out a really fun bridge we ran into in one of the Dakotas. They must have been near Mont Rushmore at least that is where I remember them and I think they were still there when we took our family along with my in-laws camping but they were called Pig tail bridges and one went over the bridge and around and went down under them. I really can not remember the point of them but they were fun. I guess sometimes you went under them and then over them. I only remember them in the Dakotas.