Buffalo Furnace was a major producer of iron in the Hanging Rock Region from 1851 to 1875 and an important Union Army supplier during the Civil War. Built by H. Hollister and Ross, its stone stack originally was 36 1/2 feet high and used a steam-powered air blast. Employing about 150 men, it could produce 15 tons in 24 hours, and its pig iron was shipped by steamboat on the Ohio River. Kentucky had been a major iron producer since 1791, ranking third in the United States in the 1830s and eleventh in 1965. Charcoal timber, native ore, and limestone supplied numerous furnaces in the Hanging Rock, Red River, Between Rivers, Rolling Fork, and Green River regions that made pig iron, utensils, and munitions. The old charcoal furnace era ended with depletion of ore and timber and the growth of railroads.