This is an east-west travel corridor of the earliest emigrant trails that continued even after the arrival of railroads and highways. Early explorers, such as John Fremont, Jedediah Smith, Osborne Russell, and missionary Narcissi Whitman were among the first to describe this route.
It was the original route of the Oregon-California Trail in 1840. The first known emigrant group to pass along the trail through the Soda Springs area was the California bound Bidwell-Bartleson Party, who began their journey in the spring of 1841. The trail was heavily used from 1849 until about 1859. The opening of the Lander Trail, which provided fresh food and water and bypassed Soda Springs, reduced travel along this route.
The establishment of a Mormon settlement at Soda Springs, coupled with the 1871 discovery of gold at Carriboo Mountain 40 miles north of the town, increased traffic along this route. These wagon roads were the only means of moving people and supplies into and through the area. After 1878, freight wagons connected with the Utah Northern narrow-gauge railroad at Arimo (then known as Oneida Station) to the west. Following the arrival of the standard-gauge Oregon Short Line railroad in 1882, Soda Springs became the primary station stop in southeastern Idaho and road traffic increased.
When the future state of Idaho was
designated as the Idaho Territory in 1863, the existing wagon routes became territorial roads under there jurisdiction of the government. It was not until well after Idaho attained statehood in 1890 that road building and maintenance became a centralized function of the state government. U.S. Highway 30 in southeastern Idaho was constructed in 1926.
"In sweeping around the point of the mountain which runs down into the bend, the river here passes between perpendicular walls of basalt, which always fix the attention, from the regular form in which it occurs, and its perfect distinctness from the surrounding rocks among which it has been placed. The mountain, which is rugged and steep, and by our measurement, 1,400 feet above the river directly opposite the place of our halt, is called Sheep rock probably because a flock of the common mountain sheep (Ovis montana) had been seen on the craggy point." - John C. Fremont, August 26, 1843