| Cannonball River | |
| Source1 Location: | Slope County in White Lake National Wildlife Refuge |
| Source1 Coordinates: | 46.47°N -103.2067°W |
| Mouth Location: | Confluence with Missouri River in Lake Oahe |
| Mouth Coordinates: | 46.4292°N -100.5892°W |
| Progression: | Cannonball River → Missouri → Mississippi → Gulf of Mexico |
| Source1 Elevation: | 2780feet |
| Mouth Elevation: | 1611feet |
| Length: | 135miles |
| Discharge1 Location: | Breien |
| Discharge1 Avg: | 250cuft/s[1] |
| Custom Label: | GNIS ID |
The Cannonball River (Íŋyaŋwakağapi Wakpá[2]) is a tributary of the Missouri River, approximately 135miles long, in southwestern North Dakota in the United States.
It rises in the Little Missouri National Grassland, in the badlands north of Amidon in northern Slope County. It flows ESE past New England, Mott, and Burt. It is joined by Cedar Creek approximately 15miles southwest of Shields and flows northeast, past Shields, forming the northern border of Sioux County and the Standing Rock Indian Reservation. It joins the Missouri in Lake Oahe near Cannon Ball. The cannonball concretions found in the vicinity of this river are the source of its name.[3]