On July 6, 1883, the first passenger train from the west on the Northern Pacific Railway arrived in Missoula. The Northern Pacific line ran along the northern boundary of the city. The second railway line in Missoula, the Milwaukee, was under construction in 1908 when a flood washed the majority of the track away. The Milwaukee line through Missoula opened in 1909 and ran alongside the Clark Fork River.
Image from 1922 Link