The town takes its name from the river that was named by Lewis and Clark: ""the stream which we suppose to be called by the Minetarus, the Musselshell River."" The name came from the mussel shells found along the river bed. Opposite the present townsite is the Musselshell Crossing, an old stockman’s landmark. Here in the 1880s, herds of Texas Longhorn cattle were bedded down just prior to being distributed to their ultimate Montana owners. The trail that connected Fort Custer and Fort McGinnis passed through here as well.