North Platte, Nebraska in the context of "South Platte River"

The North Platte River is a major tributary of the Platte River and is approximately 716 miles (1,152 km) long, counting its many curves. In a straight line, it travels about 550 miles (890 km), along its course through the U.S. states of Colorado, Wyoming, and Nebraska.

The head of the river is essentially all of Jackson County, Colorado, whose 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 border. The rugged Rocky Mountains surrounding Jackson County have at least twelve peaks over 11,000 feet (3,400 m) in height. From Jackson County the river flows north about 200 miles (320 km) out of the Routt National Forest and North Park (Colorado basin) near what is now Walden, Colorado, to Casper, Wyoming. Shortly after passing Casper, the river turns to the east-southeast and flows about 350 miles (560 km) to the city of North Platte, Nebraska.