Big Sioux River Bridge Pony truss bridge over Big Sioux River on 180th Street, 3 mi. north and 1.3 mi. west of Castlewood in Castlewood Township Open to traffic Built 1930; rehabilitated 1970
Big Sioux River Bridge Pony truss bridge over Big Sioux River on 181th Street, 2 mi. north and 1.2 mi. west of Castlewood in Castlewood Township Open to traffic Built 1934
Hidewood Creek Bridge Pony truss bridge over Hidewood Creek on 464th Avenue, 2.5 mi. north and 1 mi. west of Estelline Open to traffic Built 1900
Stray Horse Creek Bridge Pony truss bridge over Stray Horse Creek on 179th Street, 4.9 mi. east and 4 mi. north of Castlewood in Hamlin Township Open to traffic Built 1910