The Lewis and Clark Expedition became the first white men to travel the future US 93 corridor between today's Lost Trail Pass and Lolo in 1805, and Lewis's detachment ventured further north to the future site of Missoula in 1806 on their way to explore the Marias River. When US 93 was established in 1926, the nature of the highway's construction in Montana's mixture of terrain around glacial lakes, through dense forests and over high mountains was a significant challenge given the construction techniques and equipment of the time. On completed sections, animal-vehicle accidents would prove to be a thorn in the side of traveler and engineer alike.