Flows NNE, then WNW, 34 mi. to the Tagagawik River 43 mi WNW of the Nogahabara Sand Dunes, 72 mi. NW of Roundabout Mts, Nulato Hills..
Named in 1963 by W. W. Patton, U.S. Geological Survey (USGS), for the triangulation station Derby, which is so named because the 1,573 ft. hill on the right (north) bank has a distinctive shape like a derby hat.