The Willow River is a short tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Kettle River

Kettle River (Minnesota)

The Kettle is a tributary of the St. Croix River, about 80 mi long, in eastern Minnesota in the United States. Via the St. Croix River, it is part of the watershed of the Mississippi River. The river's English name is due to the large number of large rounded holes in the sandstone in and around...

 in eastern Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is one of three rivers by that name in Minnesota. Via the Kettle and St. Croix

St. Croix River (Wisconsin-Minnesota)

The St. Croix River is a tributary of the Mississippi River, approximately long, in the U.S. states of Wisconsin and Minnesota. The lower of the river form the border between Wisconsin and Minnesota. The river is a National Scenic Riverway under the protection of the National Park Service. A...

 Rivers, it is part of the watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

.

The Willow River flows for its entire length in northern Pine County

Pine County, Minnesota

As of the census of 2000, there were 26,530 people, 9,939 households, and 6,917 families residing in the county. The population density was 19 people per square mile . There were 15,353 housing units at an average density of 11 per square mile...

. It rises in the Nemadji State Forest

Nemadji State Forest

The Nemadji State Forest is a state forest located primarily in Pine County, Minnesota. A small portion of the forest extends into neighboring Carlton County. The eastern perimeter of the forest borders the state of Wisconsin. It is managed by the Minnesota Department of Natural Resources...

 in Nickerson Township

Nickerson Township, Minnesota

Nickerson Township is a township in Pine County, Minnesota, United States. The population was 154 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of 74.5 square miles , of which, 73.9 square miles of it is land and 0.6 square...

 and flows generally westwardly through Kerrick

Kerrick Township, Minnesota

Kerrick Township is a township in Pine County, Minnesota, United States. The population was 272 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of , of which, of it is land and of it is water.-Demographics:As of the census of 2000, there...

, Windemere

Windemere Township, Minnesota

Windemere Township is a township in Pine County, Minnesota, United States. The population was 1,489 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of 35.8 square miles , of which, 30.5 square miles of it is land and...

, Norman

Norman Township, Pine County, Minnesota

Norman Township is a township in Pine County, Minnesota, United States. The population was 247 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of 35.9 square miles , of which, 35.7 square miles of it is land and 0.2 square...

 and Kettle River

Kettle River Township, Minnesota

Kettle River Township is a township in Pine County, Minnesota, United States. The population was 491 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of , of which, of it is land and of it is water.-Demographics:As of the census of 2000,...

 Townships, past Duquette

Duquette, Minnesota

Duquette is a small unincorporated community in Pine County, Minnesota, United States, along the Willow River.Minnesota State Highway 23 serves as a main route in the community. The Nemadji State Forest is nearby....

. In Windemere Township it collects the Little Willow River, which rises at the town of Kerrick

Kerrick, Minnesota

Kerrick is a city in Pine County, Minnesota, United States. The population was 65 at the 2010 census.Minnesota State Highway 23 serves as a main arterial route in the community.-Geography:...

 and flows through Bruno

Bruno Township, Minnesota

Bruno Township is a township in Pine County, Minnesota, United States. The population was 179 at the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of , of which, of it is land and of it is water....

 and Norman Townships. The Willow joins the Kettle River at the town of Willow River

Willow River, Minnesota

Willow River is a city in Pine County, Minnesota, United States, at the confluence of the Kettle and Willow Rivers. The population was 415 at the 2010 census....

.