The 10 Longest Rivers in Wyoming

The state of Wyoming is located in the western mountainous region of the United States. The Continental Divide runs north-south through the state, directing the flow of rivers east and west. Most rivers east of the Continental Divide ultimately drain into the Gulf of Mexico, while those west of the divide eventually drain into the Pacific Ocean. Some of the longest rivers in Wyoming are listed below.

The 10 Longest Rivers in Wyoming

Snake River

The Snake River is the longest river in Wyoming. It covers a distance of 1,078 miles before draining into the Colombia River. The Columbia River originates in British Colombia, Canada, and flows south towards Washington and Oregon state, and later Wyoming, before draining into the Pacific. The Snake River originates in eastern Oregon, through the Snake River Plain and Hell Canyon, before discharging into the Columbia River at a rate of 54,000 cu ft/s.

Green River

The Green River is the second longest river in Wyoming. It covers a distance of 730 miles, beginning at its source in the Wind River Mountains, running through the state of Utah, before draining into the Colorado River. The Green River is the largest tributary of the Colorado River, and discharges water at an average rate of 6,121 cu ft/s.

North Platte River

The North Platte River spans a distance of 716 miles and is Wyoming’s third longest river. The river flows from Colorado, through Wyoming and into Nebraska. It begins its journey in Jackson County, Colorado, before merging with the South Platte River to form the Platte River. The Platte River drains into the Missouri River, then into the Mississippi River, and eventually into the Gulf of Mexico.

Yellowstone River

The Yellowstone River flows for 692 miles from its source at the Confluence of North and South Forks to its mouth at the Missouri River. It is Wyoming’s fourth longest river and the chief tributary of the Upper Missouri River. The Yellowstone River discharges water at an average rate of 13,773 cu ft/s.

Niobrara River

The Niobrara River flows from the High Plains of Niobrara County in Wyoming and runs for 568 miles before draining into the Missouri River. The river flows through Wyoming and Nebraska, and discharges water at an average rate of 1,718 cu ft/s.

Little Missouri River

The Little Missouri River flows for 560 miles from Crook County in northeastern Wyoming to the Missouri River in the Great Plains. The river flows through southeastern Montana, South Dakota, and into North Dakota. The Little Missouri River also flows into Theodore Roosevelt National Park before draining its waters to Lake Sakakawea, which is a reservoir of the Missouri River.

Bear River

The Bear River is the largest river in North America that does not drain into the sea. It begins at the Confluence of Hayden Fork and Stillwater Fork in the Uinta Mountains, Utah, and then flows through Wyoming and Idaho before it re-enters northern Utah and drains into the Great Salt Lake. The Bear River has a total miles of 491 miles and discharges into the lake at a rate of 2,410 cu ft/s.

Wind River/Bighorn River

The Wind River/Bighorn River covers a distance of 461 miles, stretching from Wind River Lake in Two Ocean Mountain to the Yellowstone River in Montana. The upper part of the river is known as the Wind River, but at the Owl Creek Mountains its name changes to the Bighorn River. The river discharges water into the Yellowstone River at an average rate of 3,644 cu ft/s.

Other long rivers in Wyoming include the Powder River (375 miles) and the Cheyenne River (295 miles).