Interstate 15 is the latest in a series of roads that have traversed this area since prehistory. Although used for generations by Native Americans, the first recorded use of this route was by the Lewis and Clark Expedition on August 10, 1805. They named cliffs to the north of here after the scores of rattlesnakes they encountered on their trip upriver. Within the discovery of gold at nearby Grasshopper Creek and Alder Gulch in the early 1860s, thousands of people came to southwest Montana to mine gold and to mine the miners. The originated in Corinne, Utah and traversed a series of high plateaus and narrow canyons on its way north to southwestern Montana. The road was the best route into the territory for the freighters who supplied the mining camps. Drawn by teams of mules or oxen, each wagon carried up to 12,000 pounds of freight. The trip from Utah typically took three weeks and a freighting outfit could usually make three or four round trips each years. South of here near Dell, the Montana-Utah branched into three separate trails that lead to Bannack/Deer Lodge, Virginia City, and Helena. This section of the road terminated at Helena. With the arrival of the Utah & Northern Railroad in 1880, the Montana-Utah Road became obsolete. In the 1920s, however, it again became an important travel corridor as U.S. Highway 91 and, in the early 1960s, as Interstate 15.
Slide toward Today to fade the historical sheet and see the modern map underneath.