I haven't been able to find any actual digital points for the historic river mile markers that you would find on a topographic map.
What type of source are you looking for and where? maybe check ArcGIS Hub to see if any is there
Primarily a federal source....doesn't appear to be any of the sort on Data.gov and I've never seen any such points included in NHD datasets of NHDPlus. For some of our mussel surveys, historic recordings reference these mile markers so rather than eyeballing the DRG's for them it would be great if this data existed in digital form.
Retrieving data ...