The North Platte River drainage has been an important westward route in the westward expansion of the United States. To get the two essentials, water and grass for the traveler's animals the emigration trails nearly always followed river valleys across the North American continent. These trails extended from the Missouri River, Platte River and North Platte River across Nebraska and parts of Wyoming and on to its confluence with the Sweetwater River (Wyoming). About beyond what is now Casper, Wyoming the main emigration trails left the North Platte valley and followed the Sweetwater River valley and other river valleys going further west.North Platte between Casper, WY and Pathfinder Reservoir Accessed January 18, 2023
