The Heart River is a tributary of the Missouri River

Missouri River

The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...

, approximately 180 mi (290 km) long, in western North Dakota

North Dakota

North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....

 in the United States

United States

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

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Course

The Heart River rises in the prairie

Prairie

Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...

 country of Billings County

Billings County, North Dakota

-National protected areas:* Little Missouri National Grassland * Theodore Roosevelt National Park -Demographics:As of the census of 2000, there were 888 people, 366 households, and 255 families residing in the county. The population density was 0.79 people per square mile . There were 529 housing...

, in the Little Missouri National Grassland

Little Missouri National Grassland

Little Missouri National Grassland is a National Grassland located in western North Dakota, USA. At 1,033,271 acres , it is the largest grassland in the country. Enclaved within its borders is Theodore Roosevelt National Park, which is managed by the National Park Service...

 near the south unit of Theodore Roosevelt National Park

Theodore Roosevelt National Park

Theodore Roosevelt National Park is a United States National Park comprising three geographically separated areas of badlands in western North Dakota. The park was named for U.S. President Theodore Roosevelt, in honor of his achievements in conservation as president and for the landscape's...

. It flows generally eastwardly through Stark County

Stark County, North Dakota

-Demographics:As of the census of 2000, there were 22,636 people, 8,932 households, and 5,877 families residing in the county. The population density was 17 people per square mile . There were 9,722 housing units at an average density of 7 per square mile...

 to Gladstone

Gladstone, North Dakota

As of the census of 2000, there were 248 people, 95 households, and 64 families residing in the city. The population density was 695.8 people per square mile . There were 106 housing units at an average density of 297.4 per square mile . The racial makeup of the city was 95.56% White, 1.21% Native...

, past Belfield

Belfield, North Dakota

As of the 2000 Census, there were 866 people, 355 households, and 235 families residing in the city. The population density was 799.8 people per square mile . There were 439 housing units at an average density of 405.4 per square mile...

 and South Heart

South Heart, North Dakota

As of the census of 2000, there were 307 people, 108 households, and 81 families residing in the city. The population density was 327.7 people per square mile . There were 119 housing units at an average density of 127.0 per square mile...

, through the Patterson Reservoir and past Dickinson

Dickinson, North Dakota

As of the census of 2000, there were 16,010 people, 6,517 households, and 4,020 families residing in the city. The population density was 1,690.7 inhabitants per square mile . There were 7,033 housing units at an average density of 742.7 per square mile...

. It is joined by the Green River

Green River (North Dakota)

The Green River is a tributary of the Heart River, approximately 20 mi long, in western North Dakota in the United States.It rises in the prairie country of southwestern Billings County, near Saddle Buttes, and flows ESE past New Hradec, and joins the Heart near Gladstone....

 at Gladstone, and turns east-southeastward into Grant County

Grant County, North Dakota

-Major highways:* North Dakota Highway 21* North Dakota Highway 31* North Dakota Highway 49-National protected areas:*Cedar River National Grassland *Pretty Rock National Wildlife Refuge-Demographics:...

, passing through Lake Tschida, which is formed by the Heart Butte Dam. Below this dam, the river turns northeastward into Morton County

Morton County, North Dakota

-Demographics:As of the census of 2000, there were 25,303 people, 9,889 households, and 6,932 families residing in the county. The population density was 13 people per square mile . There were 10,587 housing units at an average density of 6 per square mile...

, where it joins the Missouri at Mandan

Mandan, North Dakota

As of the census of 2000, there were 16,718 people, 6,647 households, and 4,553 families residing in the city. The population density was 1,642.8 per square mile . There were 6,958 housing units at an average density of 683.7 per square mile...

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