Horn River formed along the middle course of the Horn River, and is followed downstream by the "Second Lake". The river turns south-west, where the "Mink Lake" is formed along its course. The Laferte River also flows into the Mink Lake. Horn River then flows south, and it receives the waters of the Bluefish River before it empties into the Mackenzie River, downstream from the Great Slave Lake), immediately upstream from Mills Lake, at an elevation of . The arch made by the river defines the "Horn Plateau", a flat elevated area that rises up to ) to the north and east,
Mackenzie River Providence, which was historically an important ferry crossing in the summer, and used as an ice bridge in the winter for traffic along the Yellowknife Highway. In 2012 the Deh Cho Bridge was completed at a point about upstream, providing a safer permanent crossing. It is the only bridge across the main stem of the Mackenzie. West of Fort Providence the Mackenzie widens considerably, resembling a shallow, swampy lake more than a river; one large widening here is known as Mills Lake. After heading west for about the Mackenzie narrows and turns northwest through a long stretch of fast water