The North Platte River is a tributary of the Platte River, approximately 680 mi (1,094 km) long, in the U.S. states of Colorado, Wyoming, and Nebraska. It forms the Platte at its confluence with the South Platte River in western Nebraska. The river provides the major avenue of drainage for eastern Wyoming and western Nebraska. Although it is not navigable except at high water, it has been an important route of transportation in the westward expansion of the United States, providing the route of several of the major migration trails, including the Oregon Trail and the Mormon Trail.
The North Platte rises in the high basin of North Park located in north-central Colorado, near the town of Walden, on the eastern slope of the Park Range. It flows northward into Wyoming (through Northgate Canyon), along the western side of the Medicine Bow Mountains. On the north end of the range it is joined by the Medicine Bow River in the Seminoe Reservoir, then downstream of the Kortes Reservoir it is joined by the Sweetwater River in the Pathfinder Reservoir. Northeast of the reservoir it passes through the Alcova and Gray Reef Reservoirs and flows northeast between the Granite Mountains to the west and the Laramie Mountains to the east.
It emerges from the mountains near Casper, where it flows east, along the northern reach of the Laramie Mountains onto the Great Plains. It flows southeast across the plains of eastern Wyoming, past the town of Douglas and through Glendo and Guernsey Reservoirs. It then flows past the Fort Laramie National Historic Site, where it is joined by the Laramie River. It crosses into western Nebraska, flowing ESE between the cities of Scottsbluff and Gering. In Keith County, the Kingsley Dam forms Lake C.W. McConaughy, the largest lake in Nebraska and a significant irrigation and recreation facility for the region. East of the dam it flows nearly parallel to the South Platte, separated by only 5 mi (8 km) for a stretch of approximately 50 mi (80 km). It joins the South Platte to form the Platte just east of the city of North Platte. Historically, this river used to be a mile wide in many places as evidenced by the old streambed and written records. By the time the North Platte reaches Paxton, NE it is a muddy creek due to the extensive water taken from it for irrigation.
In Colorado and Wyoming, the river is narrower and much swifter flowing than it is in Nebraska, where it becomes a braided stream. The upper reaches of the river in the Rockies are popular for recreation rafting and fly fishing for rainbow trout and other sport fish. In western Nebraska, the banks and riverbed of the North Platte provide a green oasis amid an otherwise semi-arid region of North America.
- Bureau of Land Management: North Platte River
- Overland Trail: North Platte Crossing
- Church of Latter Day Saints: North Platte River on the Mormon Trail
- Fishing the North Platte River