The U.S. Army Corps of Engineers established a system of river mile markers along the river as a means of identifying project and structure locations. The markers use the confluence of the Missouri River and Mississippi River as a starting point and progress upstream to the headwaters of the Missouri River. Thus, the mile markers indicate how far upstream a point is from the mouth of the Missouri River.
The current system of mile markers is based on the 1960 channel. However, the river ‘s course along the segment from Gavin’s Point Dam to Ponca, NE has changed since 1960 and continues to meander today. Thus, some of the markers fall outside of the current river channel.
Mile marker posts can be seen along the 59-mile segment of the MNRR on the high bank adjacent to the river.