Location: US-85 and SD-20, Harding Cty Just after we head out of Buffalo, SD-20 will split. Location: US-85 and SD-20, Harding Cty Follow 20 east to Bison. Stay on 85 south for Belle Fourche. Location: US-85 and SD-20, Harding Cty Turn left for 20 east. Stay straight for 85 south.  E to SD-79, W to MT … Continue reading South Dakota Highway 20, US-85 to US-85