The forks meet near Nebraska Highway 97 between Mullen and Tryon.
From here the Dismal River flows east-southeast into Thomas County, crossing U.S. Highway 83 south of Thedford.
Passing just south of the Nebraska National Forest (once the Dismal River National Forest), it turns slightly to the northeast before its confluence with the Middle Loup River just East of Dunning in Blaine County.
The water comes from the Ogallala Aquifer and boils up beneath the river in places, sometimes creating areas of quicksand.
[2] Deer, coyotes, beavers, turkey and rattlesnakes inhabit the area along the river.