Bighorn is near the Yellowstone County border where the Big Horn River flows into the Yellowstone. In 1822 Col. W.H. Ashley built Fort Van Buren, two miles below the mouth of the Big Horn River, where many westbound travelers stopped for a rest. General Gibbon with 450 men crossed the Yellowstone at this point in June, 1876 as he was hurrying south to aid General Custer in a battle that had already been lost.