The Powder River runs 250 miles from its source in central Wyoming to its union with the Yellowstone River and was famously described as "a mile wide and an inch deep; too thick to drink and too thin to plow." During World War I, Montana's 91st Division gained national notoriety for the river with its war cry, "Powder River let'er buck!" The origin of the river's name is obscure: in July 1806, Captain William Clark called it the Red Stone River, and historians later supposed that the name Powder River came from the dark gunpowder-colored soil and sand along its banks, while army scout William Drannan maintained that it was inadvertently named by Vierres Roubidoux, a French guide, who shouted "Cache la Powder!" when soldiers he was escorting were attacked by Indians. In the center of Powder River Country, Broadus was once located 20 miles upstream on the Powder River in 1900, was named for a pioneer family, and was relocated to its present site at the beginning of the Homestead Boom in 1907. Its position at the junction of two important highways made Broadus an important trade center despite its great distance from any railroads, and in 1919 it became the county seat of the newly created Powder River County and was described as one of the "Biggest Little Towns in the West."