The industrial port cities of Duluth, Minnesota, and Superior, Wisconsin, and the western portion of blue Lake Superior, the largest freshwater lake in the world, are apparent in this southeast-looking, low-oblique photograph. Duluth, one of the major ports of the Great Lakes, became the chief shipping point for ore to U.S. steel mills when iron was discovered in 1865 in the Mesabi Range north-northwest of Duluth. Superior, on Superior Bay at the mouths of the Saint Louis and Nemadji Rivers, is also a shipping point for iron ore, timber, grains, and other materials to the eastern United States and the world.