moving upstream

Today we moved from Gavin's Point dam at RMM 811 to Oahe dam at RMM 1072 near Fort Pierre, SD.  Our route today was not very close to the river except for the beginning, mid point at lunch time, and at the end.  In the prairie farm land roads generally follow the north-south range lines and the east-west township lines while the river just takes the path of least resistance and meanders on an angle.