In Colorado and Wyoming, the river is narrower and much swifter flowing than it is in Nebraska, where it becomes a slow flowing, shallow braided stream. The upper reaches of the river in the Rockies in Colorado and Wyoming are popular for recreation rafting and fly fishing on the river and its many tributaries 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.