Historic Duwamish River mile marker as measured upstream from river mouth of the West distributary channel as surveyed by Corps of Engineers in 1898. River mouth was reported to have shifted to west side of what is now Harbor Island due to development of the tidelands.

Historic Duwamish River mile marker as measured upstream from river mouth of the East distributary channel as surveyed by the USC&GS in 1875. This is the same locatation as the mouth of Duwamish River in the A. Koch birds eye map of 1891.

Black River Mile marker, measured from confluence of White and Duwamish Rivers, following location of river shown on 1907 Corps of Engineers surveys.