The North River is a tributary of the Des Moines River in south-central Iowa in the United States. It is 103 mi long and drains an area of 349.2 sqmi. Via the Des Moines River, it is part of the watershed of the Mississippi River. The North River rises northeast of Casey in southern Guthrie County and flows generally eastwardly through Adair, Madison and Warren counties, past Carlisle, into southeastern Polk County, where it joins the Des Moines River 10 mi southeast of Des Moines. In Madison County, it collects a short tributary known as the North Branch North River.