The Yellowstone is navigable for about 300 m.
The principal sheep-raising counties are Custer, Yellowstone, whither many sheep are brought to be fattened, Rosebud, Beaverhead, Valley, and Meagher.
The report of Lewis and Clark attracted many traders and trappers, and within a few years the Missouri Fur Company, the Rocky Mountain Fur Company, the Hudson Bay Company and the American Fur Company had established fortified trading posts on the Missouri, the Yellowstone, the Marias, the Milk and other rivers; the most prominent among these was Fort Benton, which was established in 1846 at the head of navigation on the Missouri, and was made the headquarters of the American Fur Company.
Some light grey sandstone found in Rocky Canon, Gallatin county, looks much like the Berea (Ohio) sandstone; and a sandstone quarried at Columbus, Yellowstone county, was manufactured into grindstones equal to those made from the Berea stone.
The " Yellowstone," a steamboat sent out by the American Fur Company, ascended the Missouri to Fort Pierre in 1831 and to the mouth of the Yellowstone river in 1832.
