The route later known as the Oregon Trail had already been in regular use by traders and explorers in the early 1830s.
The trail snakes across Wyoming, entering the state on the eastern border near the present day town of Torrington following the North Platte River to the current town of Casper.
It then crosses South Pass, and exits on the western side of the state near Cokeville.
In 1847, Mormon emigrants had blazed the Mormon Trail, which mirrors the Oregon Trail, but splits off at South Pass and continues south to Fort Bridger and into Utah.
Over three hundred and fifty thousand emigrants had followed these trails to destinations in Utah, California and Oregon between 1840 and 1859.
The discovery of gold in 1863 around Bannack, Montana, has encouraged white settlers to find an economical route to the gold fields.
While some emigrants go to Salt Lake City and then north to Montana, pioneer John Bozeman and John M. Jacobs have developed the Bozeman Trail from Fort Laramie north through the Powder River country east of the Bighorn Mountains to the Yellowstone, then westward over what is now Bozeman Pass.
The trail passes through the Powder River hunting grounds of the Lakota or Western (Teton) Sioux.
A second trail, the Bridger Trail, passes west of the Bighorns but is longer and therefore less favored.
