Ironton, industrial city (1990 pop. 12,751), seat of Lawrence co., S Ohio, on the Ohio River; inc. as a city 1865. Chemicals, dyes, metal pipes, plastics, and iron products are manufactured, and some coal is mined. Ironton was a great iron-producing center during the Civil War. From c.1900 to 1910 the city had the largest blast furnace in the world, Big Etna, with a capacity of 100 tons per day. However, the development of the northern iron-ore ranges and improved transportation by rail and on the Great Lakes led to the decline of its iron industry by the early 20th cent. The remains of many giant charcoal iron furnaces are local landmarks.