The Des Moines River ( ) is a tributary of the Mississippi River in the upper Midwestern United States that is approximately 525 miles (845 km) long from its farther headwaters. The largest river flowing across the state of Iowa, it rises in southern Minnesota and flows across Iowa from northwest to southeast, passing from the glaciated plains into the unglaciated hills, transitioning near the capital city of Des Moines in the center of the state. The river continues to flow in a southeastern direction away from Des Moines, flowing directly into the Mississippi River. The Des Moines River forms a short portion of Iowa's border with Missouri between Lee County, Iowa and Clark County, Missouri. The city of Des Moines, Iowa, was named for the river.
