Quick definitions from WordNet (North platte river)
▸ noun: a river that rises in northern Colorado and flows northward into Wyoming and then eastward and southeastward through Nebraska where it joins the South Platte to form the Platte River
▸ noun: a river that rises in northern Colorado and flows northward into Wyoming and then eastward and southeastward through Nebraska where it joins the South Platte to form the Platte River