With a distance of more than 2,341 miles, the Missouri River is among the longest rivers in North America. The river also ranks among the largest on the continent in terms of volume discharge, with a maximum discharge of 0.75 million cubic feet per second. The watershed of the Missouri River is also one of the largest in North America, as it drains an area of over 0.529 million square miles, which is equivalent in size to the Canadian province of Quebec or one-sixth of the entire United States. The river is located within the United States and flows through seven states: Montana, North Dakota, South Dakota, Nebraska, Iowa, Kansas, and Missouri. Navigation along the river is hindered by the presence of natural and artificial obstacles such as waterfalls and dams, respectively. The Missouri River can reach depths up to 40 feet.
The Missouri River begins at the confluence of the Madison River and Jefferson River in Missouri Headwaters State Park, which is located near Three Forks, Montana. However, the headwaters of the river start further away. For example, the Jefferson River can be traced back to the Beaverhead River, which has its source on the slopes of Mount Jefferson. The source of the Madison River, which is in Yellowstone National Park, also represents one of the river's furthest headwaters. The river has numerous tributaries which add to its flow. Some of the main tributaries of the Missouri River include the Jefferson River, Yellowstone River, White River, Gasconade River, and Milk River.
One of the major tributaries which drains into the Missouri is the 276-mile long Osage River. Starting from its source in Vernon County, Missouri, the river flows through the states of Kansas and Missouri, and finally drains into the Missouri River near Bonnots Hill. Areas along the river’s course are densely populated and feature cities such as Lake Ozark, Warsaw, and Tuscumbia.
The Yellowstone River is among the longest of the Missouri’s tributaries, as it stretches a total length of 692 miles and is regarded as the primary tributary of the Missouri River. Starting at the confluence of the Yellowstone's South Fork and North Folk, the river flows through the states of North Dakota, Wyoming, and Montana. Over its course, the river includes numerous features such as Yellowstone Falls, where the river plunges into the Grand Canyon. The river’s mouth is situated near Buford, North Dakota, where it drains into the Missouri.
Another tributary of the Missouri is the White River. The source of the river is situated near Harrison, Nebraska, and then it flows for 580 miles through South Dakota and Nebraska before finally draining into the Missouri River. The White River is a critical source of water for the areas through which it flows, such as Badlands National Park.
Mouth of the Missouri River
In its lower regions, the Missouri is joined by one of its largest tributaries, which contribute to the river’s discharge. The mouth of the river is situated at Spanish Lake, Missouri, where it drains into the Mississippi River. The elevation of the watershed at its mouth is about 400 feet, which is significantly lower than the watershed’s elevation at its source (approximately 14,000 feet). The region near the river’s mouth is densely populated, and features cities like St. Louis, Missouri, which has a metropolitan population of nearly 3 million inhabitants.