<P> The Platte River / plæt / is a major river in the state of Nebraska and is about 310 mi (500 km) long . Measured to its farthest source via its tributary the North Platte River, it flows for over 1,050 miles (1,690 km). The Platte River is a tributary of the Missouri River, which itself is a tributary of the Mississippi River which flows to the Gulf of Mexico . The Platte over most of its length is a muddy, broad, shallow, meandering stream with a swampy bottom and many islands--a braided stream . These characteristics made it too difficult for canoe travel, and it was never used as a major navigation route by European - American trappers or explorers . </P> <P> The Platte is one of the most significant tributary systems in the watershed of the Missouri, draining a large portion of the central Great Plains in Nebraska and the eastern Rocky Mountains in Colorado and Wyoming . The river valley played an important role in the westward expansion of the United States, providing the route for several major emigrant trails, including the Oregon, California, Mormon and Bozeman trails . The first Europeans to see the Platte were French explorers and fur trappers about 1714; they first called it the Nebraskier (Nebraska), a transliteration of the name given by the Otoe people, meaning "flat water". This expression is very close to the French words "rivière plate" ("flat river"), the suspected origin of the name Platte River . </P> <P> The Platte River is formed in western Nebraska east of the city of North Platte, Nebraska by the confluence of the North Platte and the South Platte Rivers, which both arise from snowmelt in the eastern Rockies east of the Continental Divide . </P> <P> In central north Colorado is the North Park valley, ringed by mountains of 12,000 feet (3,700 m) height; this is where the North Platte River originates . The head of the North Platte River is essentially all of Jackson County; its boundaries are the continental divide on the west and south and the mountain drainage peaks on the east--the north boundary is the state of Wyoming . The nearest Colorado town is Walden, the county seat . The rugged Rocky Mountains Continental Divide surrounding Jackson County have at least twelve peaks over 11,000 feet (3,400 m) in height . From Jackson County, the North Platte flows north about 200 miles (320 km) out of the Routt National Forest and North Park near what is now Walden to Casper, Wyoming . Shortly after passing Casper, the North Platte turns to the east - southeast and flows about 350 miles (560 km) to the city of North Platte, Nebraska . In Colorado and Wyoming, the North Platte is narrower and much swifter flowing than it is in Nebraska, where it becomes a slow flowing, shallow braided stream . </P>

Where do the north and south platte rivers meet