On July 15, 1806, while descending the Yellowstone River, Captain William Clark recorded that Shield River entered the Rochejhone on its northwest side below the mountains and above a high rocky cliff, was 35 yards wide and deep, afforded a great quantity of water, and headed in snowy mountains to the northwest. During this journey, Clark named many tributaries for members of the Corps of Discovery, and this tributary, the Shields River, was named in honor of Private John Shields. Shields was a talented blacksmith who was gifted at repairing guns, tools, and other items, and the Corps often traded his knife- and ax-making skills for food and provisions from the American Indian tribes they encountered. The Shields River is one of the few rivers named after expedition members that has retained its name over time. Shields's blacksmithing experience also helped repair Captain Lewis' air gun, which he had purchased in Philadelphia.