The Oregon, Mormon Pioneer and California trails all cross Wyoming in the central and most popular corridor of the transcontinental migration of the 1840s, 1850s and 1860s. The trails followed the North Platte and Sweetwater rivers west to South Pass, after which they divided into various routes bound for Oregon, Utah or California. As many as half a million people may have traveled this corridor in the 19th century. To many, the environments of the Great Plains, Rocky Mountains and Great Basin seemed like another planet, full of strange and alien landscapes.
Emigration routes were scouted by trappers, traders, the military and early pioneers in the 1810s-1840s. As the West was settled, destinations multiplied, necessitating a complex network of routes. Emigrants sought out better routes as the immense traffic on the main routes strained natural resources of the fragile steppes and desert. Isolated wagon tracks across the West quickly grew into a far-reaching capillary system.
The Oregon/Mormon Pioneer/California Trails have been studied and assessed according to the National Trails System Act of 1968 and have been designated as National Historic Trails. Designation as a National Historic Trail (NHT) is essentially an honorary distinction, providing little protection for any of the routes. However, this identification does expressly recognize the national significance of these routes and allows the federal government to assist with studying and educating the public about these important places. The act further allows the federal government limited authority to acquire portions of these trails from willing sellers.